Children play with an old man in the Old City of Tripoli
EDITOR'S NOTE: PICTURE TAKEN ON A GUIDED GOVERNMENT TOUR. Children play with an old man in the Old City of Tripoli, August 14, 2011.

The United Nations announced on Friday it would mount an operation to evacuate thousands of foreigners trapped in Tripoli as the rebels prepare for a potential assault on the capital.

The rebels, who have made a series of advances that have brought them closer to the city, launched an assault east of the capital but were taking heavy casualties, Reuters reported.

Rebel are now in control of the areas west and south of Tripoli and say they have now cut the road links to the capital and severed the supply lines of Gaddafi's forces, shifting the conflict to their advantages.

Both NATO and the Alliance insisted they would now start targeting the leader's inner circle and Friday reports suggested that Hasan Ali, a 25-year-old student and the brother of Moussa Ibrahim, the spokesman of the Libyan government was reported killed.

His brother was killed by a NATO helicopter gunship in the central square of Zawiyah after going there with a group of others to check on friends, a Libyan official said.

"We are surprised by this and we condemn it. NATO planes have become a way of killing civilians and providing air cover for rebels to advance on Libyan cities," he said.

Friday, rebels also fought with the Gadhafi troops over the control of Zlitan, east of the capital, where fighting intensified. Despite the rebels advances Gadhafi forces are still fighting hard, and a number of wounded were being brought to the rebels' field hospital, according to Reuters.

With the conflict now becoming bloodier, a spokeswoman for the U.N.'s International Organisation for Migration (IOM), Jemini Pandya, said the organisation was planning an operation to evacuate thousands of foreigners trapped in Tripoli in the next few days.

"We are looking at all options available, but it will probably have to be by sea," she told a Geneva news conference. More than 600,000 of an estimated 1.5 million to 2.5 million foreigners, most of whom are Asian and African migrant workers, have fled six months of fighting in Libya. However, many have remained in Tripoli, which until this week was far from fighting and a safe two-hour drive from the Tunisian border," Pandya said.

Thursday, reports said that the city of Zawiyah, west of the capital, had fell to the rebels his week, blocking the road linking Tripoli to the Tunisian border.

Moussa Ibrahim however played down the rebels gains saying on state television on Thursday: "We reassure people that we are making progress on all fronts."

Despite the Gadhafi government's denial of the rebels advances, sources also said the National Transitional forces also captured the town of Sabratha, near to Zawiyah, and the town of Garyan, south of Tripoli.

Also more conflicting reports emerged after former French Prime Minister Dominique de Villepin told Le Parisien he had attended "extremely difficult" talks with both the rebels and the Gadhafi camps on Monday in a Tunisian resort, claims that had previously been denied by the Libyan government.

"I was indeed there, but I cannot make any further comment because it would compromise the chances of success," he added.

Libyan Prime Minister Al-Baghdadi Ali Al-Mahmoudi later on declined to comment further, just admitting the government had been in contact with all sides.

"You will hear in the next few days good news that will make you happy if you are for peace," he said.