BEIRUT – Syria agreed in principle Friday to allow dozens of Arab observers into the country to oversee a peace plan, a significant concession from a hardline regime that loathes any sort of outside interference.

But critics said the regime is only stalling, trying to defuse international pressure while continuing its bloody crackdown on an 8-month-old uprising which the U.N. estimates has killed more than 3,500 people.

The acceptance came after heavy pressure from the Arab League, which brokered the peace plan and this week suspended Syria from the 22-member organization for failing to abide by it. On Wednesday, the league gave Damascus three days to accept an observer mission or face economic sanctions.

Further international pressure was mounting on Syrian President Bashar Assad. Britain appointed a senior diplomat to be its pointman in dealing with Syria’s opposition over the crisis, and French Foreign Minister Alain Juppe called on the U.N. Security Council to strengthen sanctions against Assad’s regime. But Russia, which holds veto power in the council, urged caution in moving against Damascus.

The Arab League observer mission aims to prevent violence and monitor a cease-fire that Damascus agreed to last week but has not implemented.