Military commanders and activists have repeatedly called on Western powers to provide tactical helicopters for the joint UN/African Union UNAMID peacekeeping force since it arrived in Sudan's rebellious West in January 2008.
Senior UN officials said they struggled to find any of the vital aircraft because so many helicopters had already gone to other conflict zones, including Afghanistan.
On Tuesday, Sudan's neighbor Ethiopia became the first country to respond to the call by sending five tactical helicopters to Nyala, the capital of South Darfur, said UNAMID.
"This will make a huge difference ... Only one country has been able to help us. An African country has supported us," force spokesman Noureddine Mezni told Reuters.
"We still need more, at least 18 in total. Up to now we have had zero tactical helicopters ... Imagine managing without this mobility in such a huge area." UNAMID's force commander Patrick Nyamvumba told Reuters in December he urgently needed helicopters to reinforce and evacuate troops caught in the middle of clashes that still erupt in Darfur, seven years into the conflict.
Nyamvumba, a Rwandan, said UNAMID's mandate allowed it to return fire if its troops came under attack, although he did not say whether he would use helicopters to fight.
A total of 22 UNAMID soldiers and police have died in hostile action, including ambushes and carjackings, since they took over from a beleaguered African Union force at the beginning of 2008.
The lack of helicopters has also limited UNAMID's ability to monitor Darfur's vast, mostly desert territory, said UN officials speaking on condition of anonymity.
Sudanese government officials and Darfur rebel leaders gave Reuters details last week of clashes between insurgent factions and state troops in Darfur's mountainous Jabel Marra and Jabel Moun areas.
UNAMID released a statement on Tuesday acknowledging "hostilities" had taken place in those areas, but did not give details about who was fighting.
"We have reports. But we can not confirm what is going on since we are not present on the ground," said Mezni.
The Darfur conflict flared in 2003 when mostly non-Arab rebels took up arms against Sudan's government, accusing it of leaving the region underdeveloped and marginalized. Khartoum mobilised mostly Arab militias to crush the revolt, unleashing a wave of violence that Washington and some activists call genocide.
The violence has driven an estimated 2.7 million people from their homes. Estimates of the death count range from 10,000 according to Khartoum to around 300,000 according to the United Nations.
UNAMID does use a fleet of civilian helicopters, many of them contracted, for ferrying personnel.
