UPDATE: Syrian Rebel Leader Filmed Eating Soldier's Lung Has No Regrets & Promises More Slaughter (GRAPHIC VIDEO, PICTURES)

Footage of a Syrian rebel commander cutting the heart out of a soldier and biting into it has emerged online.

According to Human Rights Watch, the clip shows Abu Sakkar, a founder of the rebel Omar al-Farouq Brigade carrying out the bloody act.

He says: “I swear to God we will eat your hearts and your livers, you soldiers of Bashar the dog,” to offscreen cheering.

Scroll down to see pixellated video (WARNING, GRAPHIC CONTENT)

syrian rebel abu sakkar eats heart

Rebel leader Abu Sakkar appears to take a bite out of the soldier's heart

The person filming the incident is heard saying: “God bless you, Abu Sakkar, you look like you are drawing [carving] a heart of love on him.”

HRW’s Peter Bouckaert told Reuters: “The mutilation of the bodies of enemies is a war crime. But the even more serious issue is the very rapid descent into sectarian rhetoric and violence.”

The video comes to light as David Cameron announced Britain is to double military support for Syrian rebels to help them withstand the “onslaught” from Bashar Assad’s regime.

syrian rebel abu sakkar eats heart

'I swear to God we will eat your hearts and your livers, you soldiers of Bashar the dog'

He also suggested Russia could be ready to participate in a peace process, saying there was "real political will" to find a solution.

Cameron was speaking at a White House press conference with Barack Obama on Monday.

The British Prime Minister earlier confirmed nerve agent Sarin appeared to have been used during the two-year civil war.

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The Syrian Observatory for Human Rights recorded March as the bloodiest month of the conflict so far, with more than 6,000 people killed, including more than 500 women and children.

So far the Observatory has recorded more than 80,000 deaths but believes the real number of those killed to be much higher. The UN says more than 70,000 people have died since the uprising began in March 2011.

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  • This Friday, March 1, 2013 file citizen journalism image provided by Aleppo Media Center AMC which has been authenticated based on its contents and other AP reporting, shows a Syrian child, injured by heavy bombing from military warplanes, in the town of Hanano in Aleppo, Syria. (AP Photo/Aleppo Media Center AMC, File)

  • In this Monday, March 4, 2013 file image taken from video obtained from Ugarit News, which has been authenticated based on its contents and other AP reporting, a statue of former Syrian President Hafez Assad is pulled down in a central square in Raqqa, Syria. (AP Photo/Ugarit News via AP video, File)

  • In this Tuesday, March. 5, 2013 file citizen journalism image provided by Aleppo Media Center AMC which has been authenticated based on its contents and other AP reporting, shows a Syrian man sitting on a fallen statue of former Syrian President Hafez Assad in a central square in Raqqa, Syria. (AP Photo/Aleppo Media Center AMC, File)

  • Smoke rises following an explosion in the Syrian village of Jamlah in the southern province of Daraa, Syria, seen from the Israeli-controlled Golan Heights ,Thursday, March 7, 2013. (AP Photo/Ariel Schalit)

  • This file citizen journalism image taken on, Sunday, March. 10, 2013 and provided by Aleppo Media Center AMC which has been authenticated based on its contents and other AP reporting, shows Syrians standing next to dead bodies that have been pulled from the river near Aleppo's Bustan al-Qasr neighborhood, Syria. (AP Photo/Aleppo Media Center AMC, File)

  • Syrian rebels aim their weapons as they take position in a building during clashes with regime forces in the Salaheddine district of Aleppo in northern Syria on March 16, 2013. (JM LOPEZ/AFP/Getty Images)

  • Syrian rebels raise their weapons under a pre-Baath Syrian flag currently used by the opposition during an anti-regime protest in the northern city of Aleppo on March 22, 2013. (BULENT KILIC/AFP/Getty Images)

  • The coffins of Sunni Muslim cleric Mohamed Saeed al-Bouti and his grandson Ahmed al-Bouti, who both died in a suicide bomb attack, are carried during their funeral ceremony on March 23, 2013 at the Omayyad mosque in Damascus, Syria. (LOUAI BESHARA/AFP/Getty Images)

  • People mourn during the funeral ceremony of Sunni Muslim cleric Mohamed Saeed al-Bouti, who died in a suicide bomb attack, on March 23, 2013 at the Omayyad mosque in Damascus. (LOUAI BESHARA/AFP/Getty Images)

  • Grand Mufti of Syria Ahmad Badr al-Din Hassoun (L) takes part in the funeral ceremony of Sunni Muslim cleric Mohamed Saeed al-Bouti, who died in a suicide bomb attack, on March 23, 2013 at the Omayyad mosque in Damascus. (LOUAI BESHARA/AFP/Getty Images)

  • People pray in the Omayyad mosque courtyard during the funeral ceremony of Sunni Muslim cleric Mohamed Saeed al-Bouti, who died in a suicide bomb attack, on March 23, 2013 in the Syrian capital Damascus. (LOUAI BESHARA/AFP/Getty Images)

  • A rebel fighter fires towards Syrian government forces positions from a building in Saif al-Dawla district in the northern Syrian city of Aleppo on March 25, 2013. (BULENT KILIC/AFP/Getty Images)

  • A Rebel scouts the positions of Syrian government forces at Saif al-Dawla district in the northern Syrian city of Aleppo on March 23, 2013. (BULENT KILIC/AFP/Getty Images)

  • Rebels clash with Syrian government forces at Saif al-Dawla district in the northern Syrian city of Aleppo on March 23, 2013. (BULENT KILIC/AFP/Getty Images)

  • In this Monday March 25, 2013, citizen journalism image provided by Aleppo Media Center AMC which has been authenticated based on its contents and other AP reporting, anti-Syrian regime protesters burn a portrait for Syrian President Bashar Assad during a protest, in Aleppo, Syria. The Arabic on the poster reads, the dog of Iran." (AP Photo/Aleppo Media Center, AMC)

  • An rebel sniper aims at Syrian government forces positions from a hall in Saif al-Dawla district in the northern Syrian city of Aleppo on March 25, 2013. (BULENT KILIC/AFP/Getty Images)

  • In this Sunday, March 24, 2013 image taken from video obtained from the Ugarit News, which has been authenticated based on its contents and other AP reporting, Free Syrian Army fighters drops a shell into a firing tube, in Damascus countryside, Syria. (AP Photo/Ugarit News via AP video)

  • In this image taken from video obtained from the Ugarit News, which has been authenticated based on its contents and other AP reporting, Free Syrian Army fighters aim their weapons during clashes, in Damascus countryside, Syria on Monday, March 25, 2013. (AP Photo/Ugarit News via AP video)

  • In this Thursday March 28, 2013 image taken from video obtained from the Ugarit News, which has been authenticated based on its contents and other AP reporting, shows a building at the Syrian government checkpoint on fire, in Dael less than 15 kilometers (10 miles) from the Jordanian border in Daraa province, Syria. Thursday, March 28, 2013. (AP Photo/Ugarit News via AP video)

  • In this Thursday March 28, 2013 image taken from video obtained from the Shaam News Network, which has been authenticated based on its contents and other AP reporting, shows fighters from the Syrian Free Army firing on a Syrian army position in Dael less than 15 kilometers (10 miles) from the Jordanian border in Daraa province, Syria. Syrian rebels on Friday captured a strategic town near the border with Jordan after a day of fierce clashes that killed at least 38 people, activists said, as opposition fighters expand their presence in the south, considered a gateway to Damascus.(AP Photo/Shaam News Network via AP video)

  • In this Thursday March 28, 2013 image taken from video obtained from the Shaam News Network, which has been authenticated based on its contents and other AP reporting, shows Syrian Free Army fighters in Dael less than 15 kilometers (10 miles) from the Jordanian border in Daraa province, Syria. (AP Photo/Shaam News Network via AP video)

  • In this image taken from video obtained from the Shaam News Network, which has been authenticated based on its contents and other AP reporting, smoke rises from buildings due to shelling in Damascus, Syria, on Thursday, March 28, 2013. (AP Photo/Shaam News Network via AP video)

  • In this photo released by the Syrian official news agency SANA, plastic tables and chairs turned upside down, are seen on the floor of the open-air cafeteria at Damascus University in the central Baramkeh district, in Damascus, Syria, Thursday, March 28, 2013. (AP Photo/SANA)

  • In this image taken from video obtained from the Shaam News Network, which has been authenticated based on its contents and other AP reporting, a dead body lays on a street due to heavy fighting between Free Syrian Army fighters and government forces in Damascus, Syria, on Thursday, March 28, 2013. (AP Photo/Shaam News Network via AP video)

  • This citizen journalism image provided by The Syrian Revolution which has been authenticated based on its contents and other AP reporting, shows anti-Syrian regime protesters holding a banner and Syrian revolution flags, during a demonstration in the town of Haas in the northwestern province of Idlib, Syria, Friday, March. 29, 2013. The banner in Arabic reads: "We will continue despite killing us. We will continue although we were betrayed. We will continue and God is with us. Good news to those who are patient." (AP Photo/The Syrian Revolution)

  • This citizen journalism image provided by Edlib News Network, ENN, which has been authenticated based on its contents and other AP reporting, shows anti-Syrian regime protesters holding a placard, during a demonstration, in the town of Kafr Nabil, Idlib province, northern Syria, Friday, March. 29, 2013. (AP Photo/Edlib News Network ENN)

  • This citizen journalism image provided by Edlib News Network, ENN, which has been authenticated based on its contents and other AP reporting, shows anti-Syrian regime protesters holding a placard, during a demonstration in the town of Haas in the northwestern province of Idlib, Syria, Friday, March. 29, 2013. (AP Photo/Edlib News Network ENN)

  • This citizen journalism image provided by The Syrian Revolution which has been authenticated based on its contents and other AP reporting, shows anti-Syrian regime protesters holding banners and Syrian revolution flags, during a demonstration in the neighborhood of Bustan Al-Qasr in Aleppo, Syria, Friday, March. 29, 2013. (AP Photo/The Syrian Revolution)