Britain is to push for a "strong international response" to reports of a massacre of civilians by Syrian forces, Foreign Secretary William Hague has said.
Children are thought to be among the more than 90 people killed in the Houla area of central Syria in the past 24 hours.
Hague said the UK will press for an urgent session of the United Nations Security Council to co-ordinate the response to the "appalling" crime.
"There are credible and horrific reports that a large number of civilians have been massacred at the hands of Syrian forces in the town of Houla, including children," he said.
"Our urgent priority is to establish a full account of this appalling crime and to move swiftly to ensure that those responsible are identified and held to account.
"We are consulting urgently with our allies on a strong international response, including at the UN Security Council, the EU and UN human rights bodies.
"We will be calling for an urgent session of the UN Security Council in the coming days."
Hague urged President Bashar Assad's regime to grant "full and immediate" access to Houla for UN monitors and stop all military options, as demanded by special envoy Kofi Annan.
The Syrian Observatory for Human Rights said at least 90 people had been killed.
A local activist, giving his name as Abu Yazan, said 12 people died in shelling and 106 were killed when pro-regime thugs known as shabiha stormed the area.
The death toll is one of the highest for any single event since the popular uprising against Bashar Assad began in March 2011.
The UN says more than 9,000 people have been killed, most of them civilians.
07/13/2012 1:00 PM EDT
Car Bomb In Damascus
Syrian policemen inspect the site of a car bomb explosion on Mazzeh highway in the capital Damascus on July 13, 2012. AFP PHOTO/STR (Photo credit should read -/AFP/GettyImages)
07/13/2012 12:00 PM EDT
Susan Rice Condemns Killings
U.S. ambassador to the U.N. Susan Rice tweets:
@ AmbassadorRice :
#Syria regime turned artillery, tanks and helicopters on its own men & women. It unleashed knife-wielding shabiha gangs on its own children.
07/13/2012 11:58 AM EDT
Russia Condemns Massacre
Russia says international envoy Kofi Annan will visit Moscow on Monday to discuss the ongoing crisis in Syria. Russia also called for an inquiry into an alleged massacre that took place in the village of Tramseh on Thursday. "We have no doubt that this wrongdoing serves the interests of those powers that are not seeking peace but persistently seek to sow the seeds of interconfessional and civilian conflict on Syrian soil," Russia's foreign ministry said in a statement, according to Reuters. Moscow did not apportion blame for the killings.
Read more on Reuters.com.
07/13/2012 11:55 AM EDT
Footage Of Massacre Aftermath (WARNING: VIDEO CONTAINS DISTURBING IMAGES)
The Associated Press obtained a video that purports to show the aftermath of an alleged massacre in the village of Tramseh, near Hama.
07/13/2012 9:34 AM EDT
How Do Syrian Fighters Get Their Arms?
How do Syria's fighters get their arms? An overview put together by Reuters explains that there are three gateways to the country -- Lebanon, Turkey, and Iraq.
Syrian rebels are smuggling small arms into Syria through a network of land and sea routes involving cargo ships and trucks moving through Turkey, Lebanon and Iraq, maritime intelligence and Free Syrian Army (FSA) officers say.
Western and regional powers deny any suggestion they are involved in gun running. Their interest in the sensitive border region lies rather in screening to ensure powerful weapons such as surface to air missiles do not find their way to Islamist or other militants.
Read the full report here.
07/13/2012 9:10 AM EDT
Activists Report New Massacre (WARNING: GRAPHIC PHOTOS)
This citizen journalism image made from video provided by Shaam News Network SNN, purports to show a victim wounded by violence that, according to anti-regime activists, was carried out by government forces in Tremseh, Syria about 15 kilometers (nine miles) northwest of the central city of Hama, Thursday, July 12, 2012. The accounts, some of which claim more than 200 people were killed in the violence Thursday, could not be independently confirmed, but would mark the latest in a string of brutal offensives by Syrian forces attempting to crush the rebellion. (AP Photo/Shaam News Network, SNN)
This citizen journalism image made from video provided by Shaam News Network SNN, purports to show a man mourning a victim killed by violence that, according to anti-regime activists, was carried out by government forces in Tremseh, Syria about 15 kilometers (nine miles) northwest of the central city of Hama, Thursday, July 12, 2012. (AP Photo/Shaam News Network, SNN)
07/12/2012 6:50 PM EDT
Hama Revolutionary Council: More Than 220 Killed
According to the Hama Revolutionary Council, a Syrian opposition group, more than 220 people have been killed in a new alleged massacre in Taramseh. Earlier reports said more than 100 people were killed. "More than 220 people fell today in Taramseh," the Council said in a statement. "They died from bombardment by tanks and helicopters, artillery shelling and summary executions."
Fadi Sameh, an opposition activist from Taramseh, told Reuters he had left the town before the reported massacre but was in touch with residents. "It appears that Alawite militiamen from surrounding villages descended on Taramseh after its rebel defenders pulled out, and started killing the people. Whole houses have been destroyed and burned from the shelling," Sameh claimed.
Read more on Reuters.com.
07/12/2012 6:17 PM EDT
Syrian State TV: 'Large Numbers Of Terrorists Killed'
Syrian activist Rami Jarrah tweets that Syrian State TV has confirmed deaths in Tremseh. "Terrorists" is often the term used by the Syrian regime for opposition forces.
@ AlexanderPageSY :
Syrian State TV: clashes between security apparatus & terrorists in #Tremseh of #Hama leaves large numbers of terrorists killed #Syria
07/12/2012 5:36 PM EDT
Update: Death Toll In New Massacre Reportedly More Than 200
@ Reuters :
UPDATE: DEATH TOLL IN SYRIAN FORCES' ATTACK ON VILLAGE IN SYRIA'S HAMA REGION IS MORE THAN 200, MOSTLY CIVILIANS - OPPOSITION ACTIVISTS