Video | UN team to start probe of Libya human rights abuses

The three investigators say they will look at all alleged abuses, including those the government says have been committed by rebels or NATO forces. The team was appointed by the UN Human Rights Council following the Libyan government's crackdown on protesters.

The government claimed said it will co-operate with the inquiry.

The original mandate - to examine human rights violations allegedly committed by the forces of Libyan leader Col Muammar Gaddafi - remains the priority, says the BBC's Imogen Foulkes in Geneva, where the UN Human Rights Council is based.

The UN investigators are to present their findings to the Human Rights Council in June.  The UN Security Council has also asked the International Criminal Court to investigate Libya on possible charges of war crimes.

More recently, there have been reports that Col Gaddafi's forces trying to retake Misrata from rebels are indiscriminately shelling the city. Yesterday, three people were reportedly killed as missiles slammed into the city's port, a lifeline for those seeking to escape to the rebel stronghold of Benghazi.

Misrata has been besieged by government forces for two months, leaving parts of the city with neither electricity nor water, despite repeated claims by the Libyan government that the army would be pulling out, or that it would commence a ceasefire – neither of which took place.

Human rights groups maintain that more than 1,000 people have been killed in the fighting and many more have been wounded. Ships have been ferrying the injured to hospitals in Benghazi and bringing in humanitarian aid.

Libya's government denies it has been indiscriminately shelling civilian areas.

Misrata is the last major rebel-held city in western Libya and the fighting for it has been fierce.