US Secretary of State Hillary Clinton on Thursday urged Syria's President Bashar al-Assad to hand over power and leave his country, condemning a massacre near the town of Hama that was blamed on his supporters as unconscionable.     

Speaking in Istanbul, Clinton said the United States was willing to work with all members of the UN Security Council, which includes Russia, on a conference on Syria's political future.     

But that conference would have to start with the premise that Assad and his government give way to a democratic government, she told a news conference.     

"We are disgusted by what we are seeing," she said, referring to continuing violence in Syria. – Reuters