Syrian forces clashed on Saturday with rebels in two major cities, monitors said, despite U.N. chief Ban Ki-moon's latest rebuke to Damascus over its assault on protest hubs ahead of a peace deadline.

The U.N. secretary general strongly condemned attacks on cities across the country by forces of President Bashar al-Assad, as activists said at least 35 people, most of them civilians, were killed on Friday.

U.N.-Arab League envoy Kofi Annan has warned of "alarming" casualties as the government's year-long crackdown on dissent -- which the United Nations says has killed more than 9,000 people -- showed no signs of abating.

On Saturday, rebels attacked a military intelligence headquarters in the second city of Aleppo, as three security forces members were killed elsewhere in the province, said the Syrian Observatory for Human Rights.

Army deserters also pressed a dawn assault on Ming air base in the same northern province, said the Britain-based monitoring group.

"One officer and two security agents were killed early on Saturday at Hreitan" in Aleppo province, the site of fierce combat for the past several days, it said.

Fighting was also reported between troops and deserters in districts of Hama city in central Syria, which was confirmed by an activist on the ground, Abu Ghazi al-Hamwi.

"Regular forces launched an assault early on Saturday on the Al-Qussur district, where they burned down the house of an activist," he said.

Hamwi added that tanks also bombarded and then "attacked the town of Al-Latamna" in Hama province.

Another activist, Mohammed al-Shami, said that in Damascus province the town of Irbin saw overnight fighting following protests in support of towns being attacked by the military.

(AFP)