By Tsegaye Tadesse

ADDIS ABABA, Oct 23 (Reuters) - Governments have pledged 90 percent of the planned 26,000 troops of a new U.N.-African Union (AU) peacekeeping force for Darfur, but a lack of helicopters could hamper the mission, a military official said on Tuesday.

Talking to reporters after the AU's Peace and Security Council met in Ethiopia to discuss the operation, which is due to begin work at the start of 2008, General Henry Anyidoho said the joint force badly needed aircraft.

"Unless the helicopters are pledged, it will have a negative impact on operations," Anyidoho, a senior official with the force, told a news conference in Addis Ababa.

The United Nations has been lobbying governments to provide helicopters for the force. But officials and diplomats say no country has made a credible offer yet to supply the 24 transport and attack helicopters needed.

The force is due to replace an AU operation which lacks experience, equipment and cash. At least 10 AU troops were killed last month in an assault on their base in Darfur.

International experts estimate 200,000 have died and 2.5 million have been driven from their homes in the 4 1/2-year long war in Sudan's arid western region.

Anyidoho said the force had received pledges of more than 23,000 soldiers from African and non-African nations.

Countries outside Africa that had pledged to help included Bangladesh, Nepal, Ireland and the Netherlands, he said.

"An operational and technical advisory team of AU and U.N. officials will visit troop contributing countries to ensure troops and equipment ... are genuinely capable of operating in the harsh and hostile environment of Darfur," he said.

The visits would take place in October and November, Anyidoho added, while the command staff for the new force would be deployed in Darfur by the end of this month.

Sudan has yet to officially approve a force composition plan proposed by the United Nations, which would be 80 percent African in total, with 95 percent of the infantry African.

AlertNet news is provided by