Syrian troops on Sunday shelled the dissident province of Homs for the second consecutive day, reported opposition activists, dpa reported.
Mortar shells have been fired on the districts of Al-Khalidiya and Al-Bayada in Homs since early Sunday, said the opposition Syrian Observatory for Human Rights.
Fierce clashes were, meanwhile, reported between security forces and army defectors on the outskirts of Aleppo, in Syria's north, added the London-based observatory.
The city's police station was attacked overnight by bombs, said the group, reporting no casualty figures.
The violence came one day after the United Nations Security Council voted to authorize the deployment of an advance team of 30 unarmed military personnel in Syria to monitor a fragile ceasefire, which went into effect on Thursday.
The truce, marred by violations, is part of an international plan to end a 13-month conflict in Syria, which the UN estimates to have killed more than 9,000 people.