Syrian rebels have withdrawn from the besieged city of Homs, ending a bloody 26-day siege of the city, reports indicated Thursday.

Almost all the fighters battling Syrian President Bashar al-Assad's forces withdrew from their stronghold in the Baba Amro district of the city, leaving behind comrades to cover their retreat, Reuters reported.

A defeat in Homs, the country's third-largest city, would leave the rebels without a secure base and considerably ease the pressure on Assad's forces as well as calls from inside Syria for him to resign.

They want to take it, whatever happens, without restraint, whatever the cost, a Lebanese government official told Reuters.

Both sides had suffered heavy casualties in the fighting, with snow hampering efforts to accurately assess the numbers killed and wounded, Homs-based activist Abu Imad told Reuters.

Continued fighting and snowfall increased the misery of trapped residents short of food, power, water and telephone links, activists added.

As news of the final assault broke Wednesday night, members of the opposition Syrian National Council appealed for United Nations envoy Kofi Annan to go to Baba Amro tonight.

On Thursday, the British Foreign Secretary William Hague said the UK was closing its embassy in Damascus amid the deteriorating security situation.

We have maintained an embassy in Damascus despite the violence to help us communicate with all parties in Syria and to provide insight into the situation on the ground, he said.

Speaking to the British Parliament, Hague added the decision to withdraw embassy staff in no way reduces the UK's commitment to active diplomacy to maintain pressure on the Assad regime to end the violence.

The UN Human Rights Council voted Thursday to condemn the violence, calling on the Assad regime to end the widespread and systematic violations of human rights.

Russia, China and Cuba voted against the measure.

I think the isolation of China, Russia and Cuba is sad, but it was expected, said Eileen Chamberlain Donahoe, U.S. envoy to the council.

And I think that the meaning of this vote is almost as important for those three countries as it is for the Assad regime.

They are on the wrong side of history, and I think this outcome may help them begin to understand that they're in the wrong, the Associated Press quoted her as saying.

While previous attempts by the UN Security Council to ratify a resolution condemning the violence in Syria have also been blocked by Russia and China, Moscow is emerging as a key player in the diplomatic struggle to halt the bloodshed and growing humanitarian crisis for those trapped in combat zones.

Russia has invited Annan for talks on Syria and, according to Kuwaiti officials, will send Foreign Minister Sergei Lavrov to meet his Gulf Arab counterparts in Riyadh, Saudi Arabia next week.

According to the UN, more than 7,500 civilians have been killed by Syrian security forces since the revolt began last March.