Syria has agreed "in principle" to allow an Arab League observer mission into the country, an official said today.

But he said Syria was still studying the details.

The Arab League suspended Syria earlier this week over its deadly crackdown on an eight-month-old uprising.

The 22-member body has proposed sending hundreds of observers to try to help end the bloodshed.

The UN estimates some 3,500 people have been killed in the crackdown.

Arab League officials in Cairo, the seat of the 22-member organisation, could not be immediately reached for comment.

Syrian President Bashar Assad is facing mounting pressure from home and abroad over the country's crisis, which appears to be spiralling out of control as attacks by army defectors increase and world leaders look at possibilities for a Syrian regime without him.

French Foreign Minister Alain Juppe today called on the UN Security Council to act against Mr Assad's regime, saying the time has come to strengthen sanctions against Syria.

"We must continue to exert pressure," Juppe told a joint news conference with Turkish Foreign Minister Ahmet Davutoglu in Ankara. "The UN must act ... it is not normal for the UN Security Council not to act."

Mr Juppe said France has called on Mr Assad to change but "the regime did not want to know, which is not acceptable".

Mr Juppe said France wants to work with the Arab League and countries of the region including Turkey, as well as with the Syrian opposition.

Mr Davutoglu, responding to a question on whether his country would support a no-fly zone over Syria, said there might be a need to enforce some measures if Syria maintains its crackdown on civilians.

He said the first actions should be economic, but "other options must be evaluated later".