"We arrived in Damascus safely," Waguih Hanafy, a senior aide to Arab League chief Nabil Elaraby, said by telephone from the Syrian capital. Elaraby has said the monitors could be sent before the end of December.

They arrived in the midst of a new international uproar over activist reports that government troops killed more than 200 people in two days, with Turkey condemning President Bashar Assad over the "bloodbath."

The opposition suspects Assad's agreement to allow hundreds of Arab League monitors in after weeks of stalling is only a tactic to buy time and ward off a new round of international sanctions and condemnation.

"The Syrian regime has exploited signing the Arab League initiative to escalate the brutal military campaign against rebellious towns and cities," said Burhan Ghalioun, leader of the Syrian National Council, Syria's main opposition group.

In a statement, Ghalioun called on the UN to "urgently intervene" to stop the bloodshed, saying the Arab peace initiative was no longer enough.

Fresh raids and gunfire by government forces on Thursday killed at least 19 people, most of them in the central city of Homs and northern Idlib province, according to the British-based Syrian Observatory for Human Rights and the Local Coordination Committees.

Activists have accused government troops of a "massacre" on Tuesday in Kfar Owaid, a village in the rugged mountains near Syria's northern border with Turkey. A witness and activist groups said military forces surrounded about 110 unarmed civilians and trapped them in a valley, then proceeded to systematically kill all of them in an hours-long barrage with tanks, bombs and gunfire. No one survived the onslaught, the activists said.

Turkey, which before the uprising was a close ally of Syria, said the violence flew in the face of the spirit of the Arab League deal that Syria signed and raises doubts about the regime's true intentions.

"We strongly condemn the Syrian leadership's policies of oppression against its own people, which are turning the country into a bloodbath," the Turkish Foreign Ministry said. It added that that no administration "can come out a winner from a struggle against its own people."

On Wednesday, the Obama administration said it was "deeply disturbed" by Tuesday's attack on Kfar Owaid and accused the government of continuing to "mow down" its people.