BEIRUT -- UN cease-fire monitors toured a rebel-held town in central Syria on Sunday with army defectors, while government troops pounded a Damascus suburb with artillery and heavy machine guns, activists said.

The shelling in Douma highlighted the need for more observers a day after the Security Council approved a resolution expanding the UN observer mission from 30 to 300 members, initially for 90 days.

The expanded force is meant to shore up the cease-fire that officially took effect 10 days ago, but has failed to halt the violence that the UN says has killed more than 9,000 people since March 2011.

International envoy Kofi Annan, who brokered the cease-fire, welcomed the vote on Sunday, calling it a "pivotal moment" in the process of stabilizing the country and urged all Syrians to uphold the cease-fire.

An eight-member team is already on the ground in Syria, and since Thursday has visited flashpoints of the 13-month-long conflict.

Fighting generally halts temporarily when the observers are present in an area, but there has been a steady stream of reports of violence from towns and regions where they have not yet gone.

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

The state-run news agency SANA said UN monitors visited the central city of Hama Sunday, where they met with the governor, while opposition activists said observers visited Rastan, a rebel-held town south of Hama.

Saeed, the activist, said two people were killed Sunday by indiscriminate firing in Douma, which was the scene of intense clashes between rebels and security forces before the cease-fire went into effect more than a week ago.

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