The Syrian opposition called for an emergency meeting of the UN security council after fresh claims of regime brutality, including a video which purportedly showed an opposition activist being buried alive.

The video, said to have been filmed in the Syrian border town of Qusayr, shows a man buried to his neck in the ground. He wails desperate prayers as two men in military uniforms fill in the small ditch around his head with shovels. Dry mud and rocks smash against his face and head until he is completely covered, when the video cuts out.

The footage cannot be verified, especially as it seems to have been posted by a member of the regime forces, most likely one of the Shabiha, the informal militia often tasked with the "dirty work" on the streets to allow deniability. It may have been intended to frighten the opposition.

The dialogue on the video suggests the man has been caught sending footage of the uprising to Arab satellite television channels such as Al-Jazeera and Al-Arabiya. He cries out, "there is no god but Allah", a traditional prayer of those about to die, but is told to say "there is no god but Bashar" instead.

The call by the Syrian National Council for an emergency statement by the UN came after another apparently major breach of the ceasefire, when a huge explosion destroyed part of a working class civilian district of Hama, Mash at-Tayyaron, on Wednesday.

"We are calling for an emergency meeting of the UN Security Council so that it can issue a resolution to protect civilians in Syria," the Syrian National Council said in a statement. "Hama in recent days, and following a visit by UN observers, witnessed a series of crimes that left more than 100 people dead and hundreds wounded because of heavy shelling." The regime said "armed terrorist groups" had accidentally blown up a house they were using for bomb-making, killing 16 people including women and children. Opposition activists nearby said there had been intense tank shelling of the house, before a single large rocket hit it, killing scores of people. Earlier this week, a series of machine gun attacks by regime forces killed between 30 and 40 people, shortly after a visit by members of the Annan peace deal monitoring mission. Two monitors remain in the city. "It was a missile shot by Battilion 47, which is situated near that district," said Mousab al-Hamadee, a member of Hama´s Local Coordination Committee for the opposition. "They thought that some defectors were hiding in that part of the city."

Mr Hamadee said that many of the victims of the blast were families who had fled the violence in neighbouring Homs and had been living in the district as refugees. Activists put the body count as high as 68, including 13 children and 16 women.

Footage from immediately after the blast showed panicked crowds scrambling over the collapsed remains of buildings, and carrying the semi-naked bloodstained body of a young girl. Ash-covered men dug through the piles masonry in search of people trapped below. "Shops were closed across the whole city," said anactivist calling himself Samer al-Husain. "We left the pharmacies open do that they could provide help for the wounded.

"We had big demonstrations in several neighbourhoods. There was a smaller one in the city centre. Security forces opened fire on the demonstrators, wounding my friend who was shot in the leg." Opposition leaders in Hama declared the two monitors stationed in the city "useless".

"We called the observers yesterday night," Mr Husain said. "They came to the edge of the neighbourhood but refused to go inside. Perhaps they were scared, but I don´t know why because they had Syrian security with them."

In another allegation of regime non-compliance with the ceasefire government forces have built a concrete wall around much of the once rebel-held Homs district of Baba Amr, stationing tanks and troops near every exit, activists report.

"The only way in and out of the district are through exits heavily patrolled by security forces," said one, "Abu Bakr". "Only the elderly and children live inside Baba Amr now. The young men are wanted by the government, and mothers have sent their daughters away. They are afraid soldiers will rape them." (© Copyright of Telegraph Media Group Limited 2012. 04/27/12)