BEIRUT - Rebel fighters were forced to flee the eastern Syrian city of Deir al-Zor on Tuesday in the face of a fierce army assault, suffering the latest setback in their bid to oust President Bashar Assad.In a separate blow to their cause, a respected human rights group accused the armed opposition of committing torture and arbitrary executions during the 12-month uprising - charges previously only leveled at the state security apparatus. Despite recent successes, Assad still faces significant outside pressure. Ally Russia signaled on Tuesday it would support a UN statement backing a mission by envoy Kofi Annan to end the bloodshed so long as there was no ultimatums.In addition, Moscow joined calls for both the army and rebels to grant daily ceasefires that would enable humanitarian missions to areas of Syria worst hit by the fighting.The lightly armed rebel forces have been forced into retreat across the country in recent weeks, with the army using heavy armour to chase them from towns and cities, chalking up its latest victory in Deir al-Zor, which lies on the road to Iraq."Tanks entered residential neighborhoods, especially in southeastern areas of Deir al-Zor. The Free Syrian Army pulled out to avoid a civilian massacre," a statement by the Deir al-Zor Revolution Committees Union said.Government troops also shelled residential areas in the cities of Hama and Homs, and the nearby town of Rastan, killing at least 10 people, while a soldier died in a raid on an army checkpoint in the south, opposition sources said.Reports from Syria cannot be independently verified because authorities have barred access to rights groups and journalists.After failing to hold significant stretches of land, analysts say the rebels appear to be switching to insurgency tactics, pointing to bloody car bomb attacks in two major Syrian cities at the weekend and the sabotage of a major rail link.The United Nations says more than 8,000 people have died in 12 months of turmoil and diplomats warn the fighting could develop into a civil war pitching Assad's Alawite sect and its minority allies against the majority Sunni Muslim population.The government says 2,000 members of the security forces have been killed by foreign-backed "terrorists" and denies accusations of brutality and indiscriminate violence.Russia warms to UN statementRussia has in the past declined to back Western and Arab-backed UN resolutions condemning government violence, arguing that the actions of rebels should also be criticized.In a fresh effort to form a united international front on the mounting crisis, France has circulated a Western-drafted statement for the UN Security Council deploring the turmoil and backing peace efforts by UN-Arab League envoy Annan.Britain's UN envoy said he hoped the statement would be adopted on Tuesday, with Russia announcing it would back the text on two conditions - that there is no ultimatums and that Annan release full details of his peace plan.Annan dispatched a team of five experts to Damscus on Monday to discuss ways of implementing a peace initiative, including a mechanism to let international monitors into the country. Syria has questioned the value of such a mission.Rebels, government swap prisonerIn an unusual development, Syrian rebels released an army general abducted in the Damascus suburb of Douma in return for prisoners and bodies of insurgents and civilians held by police, an opposition source familiar with the deal said on Tuesday."Naeem Khalil Odeh has been released in return for several prisoners and 14 bodies," the source said from Douma, referring to the general, adding that he had been seized last week.The British-based Syrian Observatory for Human Rights, which has contacts throughout Syria, said army shelling had killed seven people in Homs early Tuesday, while a married couple and their child died in a mortar attack in nearby Rastan.Homs became the epicentre of the year-long rebellion against Assad and has been repeatedly targeted by government troops, who are believed to have swept most rebel gunmen from the city.There has also been fighting further to the north around Hama, and opposition sources said Syrian tanks had bombarded the city early Tuesday to try to dislodge Free Syrian Army rebels who had resumed operations there despite several army sweeps.The Free Syria Army has proved little match for Assad's well-armed security apparatus, and experts said the opposition appeared to be changing tactics.