UN Secretary-General Ban Ki-moon said that Syria's conflict is deepening and attacks on civilian areas show no sign of abating, despite assurances from Damascus that it has begun withdrawing troops under an international peace plan.
Residents of at least one area under fire from the forces of President Bashar al-Assad poured scorn on the official assertions that troops were pulling back in several cities before a ceasefire which is supposes to start on 10 April.
International envoy Kofi Annan, whose plan aims to end a year of bloodshed during the uprising against Assad, said that "more far-reaching action is urgently required" to silence the tanks and halt all forms of violence.
Addressing the United Nations Security Council, Ban gave a pessimistic assessment of the situation in Syria.
"Despite the Syrian government's acceptance of the joint special envoy's plan of initial proposals to resolve the crisis, the violence and assaults in civilian areas have not stopped. The situation on the ground continues to deteriorate," Ban said.
The United Nations says Assad's forces have killed more than 9,000 people in the conflict which began with peaceful protests, although armed rebels later began fighting back. Syria told the world body this week that 6,044 had died, including 2,566 soldiers and police.
The Security Council agreed on Thursday to a statement urging Syria to meet Annan's deadline.
UN peacekeeper due in Syria
A senior Norwegian UN peacekeeper was due to arrive in the Syrian capital of Damascus on Thursday.
Norwegian Major-General Robert Mood will discuss the deployment of observers to monitor the implementation of an international peace plan.
Syrian President Bashar al-Assad has accepted the plan, which calls for him to withdraw heavy weapons from cities, but opposition activists have reported no let-up in the violence.
Kofi Annan ha ordered Mr Mood to take an advance team to Damascus to prepare the ground for an observer mission of up to 250 unarmed staff.
Such a mission would require a UN Security Council resolution before deployment.
Meanwhile, Syrian forces pressed a crackdown on rebel bastions yesterday despite the truce pledge, with the United States voicing doubts that President Assad will comply with a peace plan deadline.
The Syrian Observatory for Human Rights said troops stormed and shelled several towns or villages, with 52 people killed around the country, including 28 civilians, with most of the casualties in the city and province of Homs.
Reports from Syria cannot be independently verified as state authorities have barred international journalists and rights groups.
While the US State Department criticised the "intensification" of violence against opponents of the regime, Russia said the opposition would never defeat President Assad's army even if "armed to the teeth”.
Rami Abdel Rahman, head of the Britain-based observatory, told AFP that "from the Turkish border in the northeast to Deraa in the south, military operations are ongoing."
The assaults were taking place despite Mr Assad's pledge to implement by 10 April a six-point peace plan brokered by Mr Annan.