A deadline set by the Arab League for Syria to sign a deal allowing monitors into the country expired on Friday without Syria's agreement, bringing the Arab body closer to imposing sanctions on Damascus over its crackdown on dissidents.

Arab foreign ministers had said in Cairo on Thursday that unless Syria agreed to let the monitors in to assess progress of an Arab League plan to end eight months of internal bloodshed, officials would consider imposing sanctions on Saturday.

The deadline expired on Friday at 1 p.m. (11 a.m. British time) without Syria's signature, an Arab League official said on condition of anonymity. Another official said the League would still consider an answer from Damascus presented by the end of Friday.

The deadline has already ended, but the Arab League leaves the door open for Syria to reply by the end of the day and if a positive Syrian response comes on Friday, then the Arab League has no objection to agreeing to it, the official said.

Secretary General Nabil Elaraby received a letter from Syrian Foreign Minister Walid al-Moualem on Friday asking a series of questions about the agreement, the Arab League said in a statement quoted by the official Egyptian news agency MENA.

It was expected today that the draft protocol between the General Secretariat of the Arab League and the Syrian government would be signed for the Arab League mission to start in Syria, it said.

Arab League officials are due to convene again on Saturday to consider sanctions if Damascus does not sign the agreement.

These could include suspending flights to Syria, stopping dealings with the central bank, freezing Syrian government bank accounts and halting financial dealings, according to a statement issued at the end of Thursday's Arab League meeting.

They could also decide to stop commercial trade with the government with the exception of strategic commodities so as not to impact the Syrian people, the statement said.

Under the Arab League initiative, Syria agreed to withdraw troops from urban centres, release political prisoners, start a dialogue with the opposition and allow monitors and international media into the country.

The Arab League suspended Syria's membership two weeks ago.

Since then hundreds of people, including civilians, members of the security forces and army deserters, have been killed as the unrest, which the United Nations says has claimed at least 3,500 lives since March, continues unabated.

(Reporting by Edmund Blair and Ayman Samir; Writing by Tom Perry; Editing by Alistair Lyon)