Khartoum - Unidentified gunmen opened fire on a peacekeeping helicopter on Monday as it flew over Sudan's Darfur region, smashing its windscreen, officials said.

The incident highlighted violent tension in the region only hours before the start of exploratory talks between Sudan's government and a powerful rebel faction.

The joint United Nations/African Union UNAMID peacekeeping mission said its Mi-8 helicopter was hit as it ferried food supplies 70km south-west of El Fasher, the force's headquarters.

"We are lucky no one was injured," said UNAMID spokesperson Noureddine Mezni. "This is a very serious incident - unacceptable. We are here to keep peace. We are not part of the conflict."

UNAMID helicopters came under fire several times last year. The force has said it fears rebel groups are targeting their aircraft, mistaking them for government helicopters which, despite regular protests, often use the same white livery.

Sudan government officials are due to meet members of Darfur's rebel Justice and Equality Movement (JEM) in Qatar late on Monday for their first official talks since 2007. JEM officials said the discussions would begin in earnest on Tuesday.

Both sides said they were planning to discuss possible confidence building measures, including a ceasefire, which could pave the way to full peace negotiations.

Sudan's government last year said it wanted to invite all Darfur rebel groups to peace talks in Doha, as part of a new peace push.

Many observers said the government's initiative was a bid to deflect pressure from the chief prosecutor of the International Criminal Court, who has asked judges to issue an arrest warrant for Sudan's president Omar Hassan al-Bashir, accusing him of orchestrating genocide in Darfur. The global court's judges are expected to rule on his request within weeks.

International experts say 200 000 people have died and 2.7 million have been driven from their homes since mostly non-Arab rebels took up arms against the government in 2003, accusing it of leaving the region underdeveloped. Khartoum says 10 000 have died. - Reuters