Libya has given Syria's charge d'affaires and his staff in Tripoli 72 hours to leave the country, the foreign ministry said in a statement.

Libya's National Transitional Council (NTC) officially recognised the Syrian opposition council in October as the legitimate authority in Syria after months of unrest against President Bashar al Assad.

"Libya had hoped that the U.N. Security Council could adopt the resolution ... to help the Syrian people live in freedom and dignity," the statement said.

Protesters earlier demonstrated outside Libyan Prime Minister Abdurrahim El-Keib's office, voicing their anger after Russia and China vetoed a weekend Security Council resolution backing an Arab plan urging Assad to give up power.

On Monday, Syrian and Libyan protesters hurled rocks, eggs and tomatoes at the Chinese embassy in Tripoli, a day after they sprayed graffiti on the walls of the Russian embassy and tore down its flag. Men replaced the Russian flag with that of the Syrian opposition and the NTC.