At least four Nigerian peacekeepers in Sudan's western Darfur region have been killed in an ambush, the UN-African Union Mission (UNAMID) says.

The attack, which happened late on Tuesday, also wounded eight peacekeepers in the West Darfur state capital El-Geneina, the peace keeping force said on Wednesday.

"The incident, which involved a Nigerian military patrol, occurred approximately two kilometres [just over a mile] from the mission's regional headquarters," the force said.

"UNAMID personnel, who were heavily fired upon from several directions, returned fire. UNAMID and local authorities are working at the scene of the incident."

Lieutenant-General Patrick Nyamvumba, UNAMID commander, called on the Sudanese government to hunt down those responsible.

"The mission condemns in the strongest terms this criminal attack on our peacekeepers who are here in the service of Darfur's people. I call on the government of Sudan to bring the perpetrators to justice," he said.

Al Jazeera's Harriet Martin, reporting from the capital Khartoum, said: "This is one of the deadliest attacks that UNAMID has experienced, bringing to a total 42 peace keepers killed since the mission was set up at the end of 2007."

"Previous attacks on UNAMID have often boiled down to a desire for either the rebels or Arab militia to get access to weapons but in this case it's not clear if they actually stole anything in this instance," she said.