David Cameron and Barack Obama today agreed to step up the pressure on Syria, including possible extra sanctions against president Bashar Assad's regime.
The Prime Minister and the US President are calling for "international unity against the regime's attacks on its own citizens", said a No 10 spokesman.
Their "disappointment" at the United Nations' stance over Assad's brutal crackdown on anti-government protesters was expressed as activists said Syrian government forces were today renewing their bombardment of the rebellious city of Homs, where more than 400 people are reported to have been killed so far this month, while humanitarian conditions worsen.
United Nations human rights chief Navi Pillay said the failure of the UN Security Council to take action has encouraged Damascus to make an "all-out assault" on the rebels.
Downing Street criticised the security council's failure this month to agree a resolution condemning Assad's regime. Mr Cameron and Mr Obama, who have already called on Assad to step down, discussed the latest violence in a transatlantic phone call last night, when, said the Downing Street spokesman, they "expressed disappointment at the Russian and Chinese vetoes of the draft [UN resolution]" and agreed on the need for further UN action.
Meanwhile, a push by government tanks into the rebel-held central town of Rastan has been repelled. The offensive began yesterday, a day after Syria rejected Arab League calls for the UN to create a peacekeeping force in the country, and for an end to the crackdown on dissent.
Damascus called the league's initiative "a flagrant interference" in its internal affairs and "an infringement upon national sovereignty".
The Syrian uprising started 10 months ago. More than 5,400 people are said to have been killed there last year, while tens of thousands have been arrested, with more than 18,000 still detained. Thousands more are missing, 25,000 are estimated to have fled the country and more than 70,000 are internally displaced.
Army defectors clash almost daily with soldiers. The rebels have taken control of small swathes of central Homs province, where Rastan is located, and the north-western province of Idlib, which borders Turkey.
