New York - Chad's government forces were fighting off rebel troops advancing towards the town of Abeche and the capital N'Djamena, the United Nations said Friday.

The UN said government troops backed by jet fighters and helicopters fought the rebels on the ground while a second column of rebels in eastern Chad has moved to the south of the country near the border with the Central African Republic (CAR).

It also reported that a third column of rebels was just across the eastern Chadian border in Sudan's Darfur, west of El Geneina. Each column had between 50 and 100 vehicles, the UN said in a report to the UN Security Council.

The fighting intensified this week between the government and the two first columns of rebels, forcing the evacuation of non-essential staff of three UN relief agencies and 11 non-governmental organizations to Goz Beida, where they can be under the protection of the UN mission overseeing the border between Chad and CAR.

The mission, with currently about 2,400 military and civilian personnel, is responsible for the wellbeing of hundreds of thousands of refugees in the border areas, many of whom fled the ethnic war in Darfur. (dpa)