Syria's army rained shells on rebel bastions in and around Damascus Tuesday and sent extra troops to second city Aleppo, as a watchdog said the death toll from 18 months of violence now topped 31,000.
US President Barack Obama on Wednesday held a video conference with Afghan President Hamid Karzai focusing partly on an unprecedented wave of attacks on NATO troops by their local comrades.
At Sayyed Ali Square in central Aleppo, rebels cry out "Allahu Akbar" (God is greatest) to which Syrian government troops respond "You will soon join him," before the shooting starts up again.
Russia said Saturday it would be "naive" for outside powers to expect Syrian President Bashar al-Assad to withdraw his troops first from major cities and then wait for the opposition to follow suit.
Britain's military will take two years to return to normal after it was called upon to provide 18,000 troops for the London Olympics, the chief planner warned in an interview published Tuesday.
Syrian troops and rebels fought pitched battles near an intelligence headquarters in Aleppo on Tuesday as a military offensive in Syria's commercial capital raged into a fourth day.
Britain has drafted in another 1,200 troops to plug a security gap at the London Olympics left by the failure of a private security firm to provide enough guards.
Arab nations have called on Syrian President Bashar al-Assad to swiftly give up power as his troops launched a fresh assault on rebels in Damascus and the second city Aleppo.
British security firm G4S said Friday it expects losses of up to $77 million after the government had to deploy extra troops for the Olympics because the company failed to provide enough guards.
Syrian troops with tanks and helicopters slaughtered more than 150 people in a central village, rights activists said on Friday, prompting the opposition to call for urgent UN intervention.
Britain's army will have to provide extra troops to police Olympic venues as a private security firm cannot supply enough trained staff, while a watchdog warned Thursday that border staff are under-trained.
