The US and the European Union demanded on Thursday that Syrian President Bashar al-Assad step down over his brutal crackdown of pro-democracy protesters.
President Obama said the time had come for the Syrian leader to “step aside”.
US Secretary of State Hillary Clinton promised that new US financial sanctions would “tighten the circle of isolation” around Assad’s government.
Meanwhile a United Nations investigative team warned that Syria’s violent response to demonstrators may constitute crimes against humanity.
Their report claims that more than 1900 people have been killed by government troops – who often fired on peaceful protesters without warning and at close range.
The team urged the UN Security Council to “consider referring the situation to the International Criminal Court”.
Diplomats are due to be briefed on the report later.