The former al-Qaeda leader believed to have been behind the Algerian hostage attack has reportedly been killed.

Mokhtar Belmokhtar was killed by Chadian soliders in Mali, Reuters reported.

Foreign Secretary William Hague said Belmokhtar's death would be "a blow for terrorism" but added that he could "not absolutely confirm" the reports.

Chadian state television announced the death of the Islamist militant, who is said to have ordered January's deadly assault on an Algerian gas plant.

The French military, which is leading the offensive in northern Mali, said it could not confirm the information.

One-eyed Belmokhtar is known as "Mr Marlboro" because of his links to cigarette smuggling in the region.

Army Chief of Staff Gen. Zakaria Ngobongue read a statement saying Chadian soldiers on Saturday had destroyed a jihadist base in the Adrar and Ifoghas mountains of North Mali, killing Belmoktar.

The purported death of Belmokhtar comes a day after Chad's president said their troops killed Abou Zeid, the other main al-Qaida commander in the region.

Speaking on the BBC's Andrew Marr show, Hague said: "These are reports from Chadian soldiers who have been fighting in northern Mali.

"We can't absolutely confirm this at the moment, and I stress that, but it would be a blow to terrorism."

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  • Algeria

    Hundreds of Algerians worked at the gas plant, but the Algerian media says most have been released. The Norwegian energy company Statoil says three of its Algerian employees are hostages. <em>Caption: This image from video provided by the SITE Intel Group made available Thursday Jan. 17, 2013, purports to show militant militia leader Moktar Belmoktar. (AP Photo/SITE Intel Group) </em>

  • Norway

    Nine Norwegian employees of Statoil are hostages, the company says. <em>Caption: Norwegian Prime minister Jens Stoltenberg, right, and Foreign Minister, Espen Barth Eide, attend a press conference in Oslo regarding the attack on Statoil's plant in Algeria, where 13 Norwegians are among 17 workers who were taken as hostages, Wednesday, Jan. 16, 2013. (AP Photo/NTB Scanpix, Berit Roald) </em>

  • United States

    Seven Americans were hostages, the militants said, but they claimed only two survived the Algerian strafing Thursday. The U.S. has confirmed that some of its citizens are hostages but gave no numbers. <em>Caption: Defense Secretary Leon Panetta pauses during a news conference in Rome, Wednesday, Jan. 16, 2013. Panetta confirmed on Wednesday that American citizens are among the hostages taken by an Al Qaeda-linked group that seized a gas field in Algeria, calling the action a "terrorist attack," (AP Photo/Jacquelyn Martin)</em>

  • Britain

    Several" British nationals are among the hostages, the U.K. government says. <em>Caption: Statoil spokesman Ole Anders Skauby, centre right, talks to TV reporters outside Scandic Bergen Airport hotel where a drop-in center is established for relatives of hostages involved in the situation in Algeria. (AP Photo / Hakon Mosvold Larsen / NTB scanpix) </em>

  • Malaysia

    Two Malaysians being held, the government says. <em>Caption: This April 19, 2005 photo released by Statoil via NTB scanpix, shows the Ain Amenas gas field in Algeria, where Islamist militants raided and took hostages Wednesday Jan. 16, 2013. (AP Photo/Kjetil Alsvik, Statoil via NTB scanpix) </em>

  • Ireland

    A 36-year-old Irish man was among the hostages but is now safe and free, according to Ireland's government. <em>Caption: This April 19, 2005 photo released by Statoil via NTB scanpix, shows the Ain Amenas gas field in Algeria, where Islamist militants raided and took hostages Wednesday Jan. 16, 2013. (AP Photo/Kjetil Alsvik, Statoil via NTB scanpix) </em>

  • France

    President Francois Hollande says there are French hostages but gave no exact number. <em>Caption: In this undated image released Wednesday Jan. 16, 2013, by BP petroleum company, showing the Amenas natural gas field in the eastern central region of Algeria, where Islamist militants raided and took hostages Wednesday Jan. 16, 2013. (AP Photo/BP)</em>

  • Romania

    Romania's Foreign Ministry says Romanians are among hostages. <em>Caption: In this undated image released Wednesday Jan. 16, 2013, by BP petroleum company, showing the Amenas natural gas field in the eastern central region of Algeria, where Islamist militants raided and took hostages Wednesday Jan. 16, 2013. (AP Photo/BP)</em>

  • Japan

    At least three of the hostages are Japanese, according to the Japanese media. <em>Caption: Employees arrive for work at the headquarters of JGC Corporation, or Nikki in Yokohama, near Tokyo Thursday, Jan. 17, 2013, a day after an attack at a natural gas complex in Algeria which involves the company's workers. (AP Photo/Kyodo News) </em>