Beirut ? The Arab League halted its observer mission in Syria on Saturday because of escalating violence that killed nearly 100 people the past three days, as pro-Assad forces battled dissident soldiers in a belt of suburbs on the eastern edge of Damascus in the most intense fighting yet so close to the capital.

The rising bloodshed has added urgency to new attempts by Arab and Western countries to find a resolution to the 10 months of violence that according to the United Nations has killed at least 5,400 people as Assad seeks to crush persistent protests demanding an end to his rule.

The United Nations is holding talks on a new resolution on Syria and next week will discuss an Arab peace plan aimed at ending the crisis. But the initiatives face two major obstacles: Damascus’ rejection of an Arab peace plan, which it says impinges on its sovereignty, and Russia’s willingness to use its U.N. Security Council veto to protect Syria from sanctions.

Syria’s Interior Minister Mohammed Shaar vowed the crackdown would go on, telling families of security members killed in the past months that security forces “will continue their struggle to clean Syria’s soil of the outlaws.”

Government forces launched a heavy assault on a string of suburbs and villages on the eastern outskirts of Damascus, aiming to uproot protesters and dissident soldiers who have joined the opposition, activists said.

Troops in tanks and armored personnel carriers attacked the suburbs of Kfar Batna, Saqba, Jisreen and Arbeen, the closest of which lie only a few miles from downtown Damascus, said the Local Coordination Committees activist network and the British-based Syrian Observatory for Human Rights. Dissident troops were fighting back against the attackers, they said.

In a nearby suburb, Douma, gunmen ambushed a bus carrying army officers, the state-run news agency SANA, calling the attackers “terrorists.” It said seven officers were killed.

The assault in the suburbs seemed to be a sign of the growing presence of dissident soldiers closer to the capital. Although the tightly controlled Damascus has been relatively quiet since the uprising began, its outskirts have witnessed intense anti-regime protests and army defectors have become more visible and active in the past few months.

“The fighting today is the most intense near the capital since the uprising began,” said Rami Abdul-Rahman who heads the Observatory for Human Rights. “The Syrian regime is trying to finish the uprising militarily now that the case is being taken to the United Nations.”