Dubai: UN-Arab League envoy Kofi Annan called on both Syrian government forces and opposition fighters to put down their weapons and work with the unarmed observers to consolidate the fragile ceasefire that took effect 10 days ago.

"The government in particular must desist from the use of heavy weapons and, as it has committed, withdraw such weapons and armed units from population centres and implement fully its commitments under the six-point plan," Annan said, referring to his plan accepted by both sides to end 13 months of violence. On the ground, UN ceasefire monitors toured a rebel-held town in central Syria yesterday with army defectors, while government troops pounded a Damascus suburb with artillery and heavy machine guns, activists said.

Opposition unity talks

"This UN observers' thing is a big joke," said Douma-based activist Mohammad Saeed. "Shelling stops and tanks are hidden when they visit somewhere, and when they leave, shelling resumes."

Syria's opposition and its western supporters suspect President Bashar Al Assad is largely paying lip service to the truce. Syria's state-run news agency Sana said UN monitors visited the central city of Hama where they met with the governor, while opposition activists said observers visited Rastan, a rebel-held town south of Hama.

In Cairo, a spokeswoman for the opposition Syrian National Council, Bassma Kodmani, called for the number of UN monitors in Syria to be raised to at least 3,000, saying the current 300 approved by the UN would not be enough. She told reporters after a meeting with Arab League chief Nabeel Al Arabi that Syrian opposition factions would meet in Cairo on May 15 at the League headquarters to try and unify their ranks.

Despite relative calm in Homs, the Syrian Observatory for Human Rights said six people were killed in the province by government forces.

The deaths raised to 17 the number of people killed yesterday across Syria, including two civilians and four soldiers who died during an assault on a rebel bastion near Damascus by regime forces, activists said.