BEIRUT - A senior Norwegian UN peacekeeper flies into Damascus on Thursday to try to broker an agreement that will allow observers to be deployed across Syria to monitor a ceasefire demanded by an international peace plan.

Syrian President Bashar al-Assad has accepted the plan, which calls for him to withdraw heavy weapons from cities, and his ally Russia said Syrian forces had begun to pull back.

But opposition activists on Wednesday reported no let-up in Assad's crackdown on what began over a year ago as a peaceful uprising and has since turned at least partly into an armed insurgency.

They said at least 80 people, 18 of them soldiers, had been killed in the previous 24 hours. Shells rained down on Homs, the city of 1 million that has suffered most in the uprising.

"Since this morning they have been shelling Khalidiya neighbourhood, that is in its 17th day," said activist Hadi Abdullah by telephone from Homs.

UN-Arab League special envoy Kofi Annan has ordered Norwegian Major-General Robert Mood, who served as head of mission of UNTSO, the UN peacekeeping operation in the Middle East, to take an advance team to Damascus anyway.

Mood's job is to prepare the ground for an observer mission comprising up to 250 unarmed staff, his spokesman Ahmad Fawzi said. Such a mission would require a UN Security Council resolution before deploying.

Annan has brokered a six-part peace plan that provides for an April 10 withdrawal of Syrian forces, to be followed by a ceasefire by rebel forces within 48 hours.    

Assad's government issued its latest official death toll for the 12-month uprising. It told the United Nations that 6,044 people had been killed, of whom 2,566 were soldiers and police.