BEIRUT - The United Nations expressed grave concern about twin suicide car bombings in Damascus and condemned the attacks that killed 44 people and lent a grim new face to the uprising in Syria.

With world powers arguing about details of a UN resolution on Syria, UN Secretary-General Ban Ki-moon called for an immediate end to the bloodshed and urged the Syrian government to implement a peace plan proposed by the Arab League.

The first batch of 50 Arab League monitors will head to Syria on Monday to assess whether Damascus is abiding by an Arab peace plan, Egypt's state news agency reported on Friday.  

European and US officials want the UN Security Council to impose an arms embargo and other sanctions on Syria's government because of its nine-month-old crackdown on protesters against the rule of President Bashar al-Assad, which UN officials say has killed more than 5,000 people.

The suicide bombs, aimed at two security buildings, sent human limbs flying and streets in Syria's capital were littered with human remains and the blackened hulk of cars.

Foreign Ministry spokesman Jihad Makdesi said the attacks were carried out by "terrorists (trying) to sabotage the will for change" in Syria, and followed warnings from Lebanon that al Qaeda fighters had infiltrated Syria from Lebanese territory.    

Some of Assad's opponents said the suicide attacks could have been staged by the government itself.        

The UN Security Council condemned the "terrorist attacks".

"Terrorism in all its forms and manifestations constitutes one of the most serious threats to international peace and security, and ... any acts of terrorism are criminal and unjustifiable," its statement said.