Syrian tanks attack eastern city of Deir al-Zour 7 August 2011 Last updated at 10:29 GMT

Deir al-Zour has been one of the main focal points of the unrest that began in mid-March

At least 20 people have died after the Syrian army stormed Deir al-Zour, the largest city in the east and a scene of frequent protests, activists say.

Scores of tanks and armoured vehicles are reported to have entered several areas of the city after a heavy bombardment that began before dawn.
At least four other people have been killed in Homs province, activists say.
Earlier, the UN secretary general told President Bashar al-Assad to stop using troops against civilian protesters.
In a telephone call on Saturday, Ban Ki-moon "expressed his strong concern and that of the international community at the mounting violence and death toll in Syria over the past days", a UN spokesman said.
It was the first such communication in several months; the UN says Mr Assad had been refusing to accept calls from the secretary general.
Activists say at least 1,650 civilians have been killed and ten of thousands arrested since the uprising began in mid-March.
International journalists have been prevented from reporting on events inside Syria, making it difficult to verify the reports.
City 'totally paralysed' Activists said the bombardment of Deir al-Zour, about 450km (280 miles) east of Damascus, began at dawn on Sunday, with scores of tanks and armoured personnel carriers moving into many parts of the city, to the sound of loud explosions and machine-gun fire.

"Shelling has been heard in several areas," Mr Abdel Rahman told the AFP news agency.

The Local Co-ordination Committees, an activist group that documents and organises protests, said nine districts had been stormed, but that the gunfire was heaviest in al-Joura, where snipers now occupied the rooftops of most of the area's high buildings.
Activists said people were unable to flee because troops were all around, but also that some of the soldiers in al-Joura had defected rather than shoot at people. Some were now trying to protect the civilians, they added.
Earlier this week, residents had reported the build-up of soldiers and tanks, which they said were trying to divide the city into smaller parts.
State media also foreshadowed the assault, saying local leaders had called on the army to enter Deir al-Zour "to protect the citizens and preserve the public and private properties".
Parts of the city were shelled on Thursday night and Friday morning, witnesses said. Some reported shortages of food and water.
"Conditions in the city are very bad since it has been under siege for nine days," one activist told the Associated Press. "There is lack of medicine, baby formula, food stuff and gasoline. The city is totally paralysed."
Despite the imminent threat of an assault, tens of thousands of demonstrators took to the streets after Friday prayers, chanting: "We don't want the army inside the cities".
The BBC's Jim Muir in Beirut says Deir al-Zour, on the Euphrates river and not far from the border with Iraq, is in a strongly tribal area.
Some tribal leaders have declared loyalty to the regime, but not all. Last month, security forces arrested Sheikh Nawaf al-Bashir, a senior leader.

'Excess force'
Mr Abdel Rahman also told AFP that security forces backed by tanks had killed four civilians and wounded several on Sunday in the central town of Hula, in Homs province. The Local Co-ordination Committees said seven people were killed in a bombing raid on the town.
The army also continued its siege on the central city of Hama, which has become the centre of the uprising. Earlier, the Local Co-ordination Committees said the number of those killed since security forces launched an assault last Sunday was now more than 300.
On Saturday, funerals were held for several of the more than 20 people killed on Friday. Amateur videos posted online showed crowds marching through the central Damascus district of Midan. Some chanted: "There is no God but God and Assad is his enemy."
The official Sana news agency said funerals were also held for six security forces personnel shot dead by "terrorist groups" in Homs, Hama and the northern province of Idlib.
"GCC countries... call for an immediate end to the violence and any armed appearances, as well as an end to the bloodshed," it said. In addition, Turkish Prime Minister Recep Tayyip Erdogan announced that Foreign Minister Ahmet Davutoglu would visit Syria on Tuesday. He said Turkey could not "remain a spectator" to events across the two countries' long shared border.
Syrian Foreign Minister Walid Muallem said the government would press ahead with political reforms and hold "free and transparent" elections before the end of 2011 which would "give birth to a parliament representing the aspirations of the Syrian people".
"The ballot box will be the determining factor and it will be up to the elected parliament to review adopted draft bills to decide on them," he told foreign ambassadors in Damascus.
Later, security forces had arrested the prominent opposition figure and former political prisoner, Walid al-Bunni, and his two sons, activists said. Four activist brothers from the Khattab family were also detained.