Syrian rights groups say dozens more killed

Activists said at least 38 people were killed in a tank assault on the eastern city of Deir al-Zor, despite a direct UN appeal to the country's president to stop using military force against civilians.

UN chief Ban Ki-Moon has said he is alarmed by the escalating violence and warned President Bashar al Assad to end the military crackdown.

In a phone conversation, Ban told President Bashar al Assad of his "strong concern and that of the international community at the mounting violence and death toll in Syria over the past few days".

The UN said Ban also "urged the president to stop the use of military force against civilians immediately".

Ban has been trying to speak to Assad for months but the Syrian leader had been refusing to take his calls.

The conversation comes days after the UN Security Council condemned Damascus' bloody crackdown on civilian protesters, the 15-nation body's first substantive action on Syria's five-month-old uprising.

The statement from the UN said Assad referred to "the large number of lives lost among the security forces and police," an assertion that the Syrian government has made repeatedly since the crackdown began.

However, the assertion is one which Western diplomats have voiced doubts about.

"The Secretary-General said he condemned the violence against both the civilians as well as security forces," the statement said.

Referring to President Assad's promises of reform, the Secretary-General said that for the measures to "gain credibility", force must "stop immediately".