Beirut: Syrian government troops shelled suburbs of the capital Damascus, killing at least 12 people in a stepped-up regime offensive on rebel areas around the country, activists said on Saturday.

Most of the deaths occurred overnight in the restive suburb of Douma, where activists said regime forces fired mortars that struck a residential building, killing eight people.

Douma-based activist Mohammad Saeed and the Observatory, which relies on a network of activists on the ground, said that four people were killed in the shelling of Arbeen and Tall suburbs.

“The regime is trying to purge the suburbs of the capital of all resistance,” Saeed said. He said the fire on the suburbs was indiscriminate and that a man, his wife and their child died when a mortar shell hit their apartment in Arbeen.

Saeed said UN observers deployed in Syria to monitor the ceasefire, which never really took hold, have not been to Douma in over a week. “But anyway, all they can do is record what they see, they cannot help,” he said.

There are nearly 300 monitors currently in Syria to follow up on a peace plan brokered by special international envoy Kofi Annan, which now seems to be disintegrating. The regime and the opposition have ignored the ceasefire, which was supposed to go into effect on April 12, and the recent escalation is raising questions about how effective the unarmed monitors can be in a conflict that every day looks more like a civil war.

Western powers have pinned their hopes on the Annan plan, in part because there are no other options on the table. There is little support for military intervention, and several rounds of sanctions have failed to stop the bloodshed.

Activists say some 14,000 people have been killed since the uprising against President Bashar Al Assad began in March 2011. The uprising began as a largely peaceful protest movement but has since morphed into an insurgency seeking to topple the regime.

The Observatory said more than a hundred people were arrested in government raids conducted Saturday in the capital Damascus. Gunfire and explosions could be heard during the raids in the Basatin district and the restive Kfarsouseh area where rebels clashed with government troops for hours in June.