An advance team of Arab League observers has arrived in Syria, amid a mounting death toll from a crackdown on opposition unrest.

The team arrived on Thursday to lay the groundwork for Arab League monitors who arrive over the coming weeks. The monitors will see whether Syria follows through on a pledge to stop attacks on anti-government protesters.

Activists say at least 21 people were killed on Thursday, following security force raids and clashes. The Syrian Observatory for Human Rights says nine of the deaths were in the flashpoint region of Homs.

Syria's government agreed to allow the observers into the country under global pressure to stop its bloody crackdown on dissent.

The Arab League has also been urging Syria to withdraw its security forces from neighborhoods and begin talks with the opposition.

Syrian opposition groups say troops have killed at least 250 people since Monday — one of the bloodiest periods since the uprising began in March.

Meanwhile, the opposition Syrian National Council is urging the U.N. Security Council to hold an emergency meeting on the situation. It also wants the U.N. to declare safe zones inside Syria.

Russia's U.N. ambassador, Vitaly Churkin, says Security Council members will hold more talks Thursday to “build consensus” on a Russian-sponsored draft resolution on Syria.

Turkey on Thursday condemned its neighbor, saying Syria's policies were turning the country into a “bloodbath.” A Turkish Foreign Ministry statement said the violence raises serious concerns about Syria's true intentions, and that no administration can be a winner in a struggle against its own people.

On Wednesday, a spokesman for the U.S. administration said it is only a matter of time before the regime of Syrian President Bashar al-Assad comes to an end.

The United Nations says at least 5,000 people have been killed during the uprising against Mr. Assad's government. Syrian authorities blame the violence on “armed terrorist groups.”