The Arab League has given Syria a deadline to accept Arab monitors under a plan to end an eight-month crackdown on protests or risk economic sanctions.
If Syria fails to sign an agreement in Cairo by 11:00 GMT the Arab League will meet on Saturday to decide what sanctions to impose, the BBC reports.
The League says it made the decision after Damascus pursued violent measures against protesters, even though it said it had accepted an Arab peace plan this month.
Activists say at least 40 people, including six children, have been killed across Syria in the past three days.
The UN estimates more than 3,500 people have died since the protests began in March.