The UN observer mission in Syria on Monday expressed concern about escalating violence in the central city of Homs and said it was trying to negotiate the evacuation of civilians.
"The impact from heavy artillery shelling and machinegun firing was heard and seen over the neighborhood of Khaldiyeh in the city center," the UN Supervision Mission in Syria said in a statement.
"UNSMIS has also received reports of a large number of civilians, including women and children trapped inside the town and are trying to mediate their evacuation."
It added that reports of a large number of casualties could not yet be confirmed.
Activists said Khaldiyeh and two other neighborhoods were under siege and Red Crescent teams were blocked access.
UN observers also reported heavy fighting in Rastan and Talbisa, north of Homs "with artillery and mortar shelling, as well as firing from helicopters, machine guns and smaller arms," the UN statement said. "In Talbisa, UN observers reported that the Free Syrian Army captured Syrian Army soldiers."
According to the Syrian Observatory for Human Rights, at least 74 people were killed across Syria on Monday.
Overall, the 15-month revolt against the regime of President Bashar al-Assad has left more than 14,100 people dead.
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