Syrian troops backed by tanks have stormed a Damascus suburb, activists said as an advance team of UN ceasefire observers continue their tour of flashpoint areas to lay the groundwork for an expanded monitoring mission.
Activists said that explosions shook the town of Douma early on Sunday as soldiers launched an operation there to crush an armed rebellion against President Bashar al-Assad.
Activist video posted online showed columns of smoke billowing into the sky over Douma, 10km north of Damascus. Three people have reportedly been killed there.
The reports of violence comes as Kofi Annan, the Arab-UN envoy, asked the Assad government and the opposition to immediately halt violence and the use of heavy weapons.
"I urge all forces whether governmental, opposition or others to put down their weapons and work with the United Nations monitors to consolidate the fragile cessation of violence in all its forms," Annan said in a statement.