U.S. President Barack Obama on Saturday called for Syrian President Bashar al-Assad to stop killing and step aside for a democratic transition in his country.

Obama charged that the Syrian government "murdered" hundreds of Syrian citizens the day before, including women and children, in Homs "through shelling and other indiscriminate violence," and that Syrian forces continue to prevent hundreds of injured civilians from seeking medical help.

"I strongly condemn the Syrian government's unspeakable assault against the people of Homs and I offer my deepest sympathy to those who have lost loved ones," he said in a written statement.

"Assad must halt his campaign of killing and crimes against his own people now. He must step aside and allow a democratic transition to proceed immediately."

"Assad has no right to lead Syria, and has lost all legitimacy with his people and the international community," Obama said.

World powers are wrangling over a Morocco-drafted resolution on Syria at the UN Security Council, which echoes an Arab League initiative envisioning Assad's handing over power to his deputy to pave the way for an election. Russia, a veto-wielding Council member, voiced strong opposition to the draft.