"With the effort of the concerned agencies and by communication with tribal leaders ... we have been able to release the two Jordanians safely. They are now in their base," Moawia Osman, a ministry spokesman, said.

The Jordanian officers were seized on Saturday by armed men in Nyala, capital of South Darfur state.

The two had been walking to a Unamid transport dispatch point, and were 100 metres from their residence in the city's Almatar area when they were blocked by three individuals in a 4x4 vehicle, the statement said.

'Targets of violence'

It was the third time since August 2009 that Unamid forces has been the target of an abduction in the volatile region of Darfur.

In April, four South African peacekeepers were seized after two other members of the mission had been taken in August last year. All of them were freed unharmed.

"A trend of abductions of humanitarian workers which started last year is particularly alarming"

John Holmes,
UN undersecretary general for humanitarian affairs

At least 19 foreigners have been abducted in Darfur since March 2009. All have since been freed, except an American aid worker with the Samaritan's Purse group who was abducted in May, whose captors are demanding a ransom.

"Humanitarian personnel and assets in Darfur also continue to be regular targets of violence," John Holmes, the UN's undersecretary general for humanitarian affairs, said on Saturday.

"A trend of abductions of humanitarian workers which started last year is particularly alarming."

The abductions place increased pressure on the peacekeeping and humanitarian operation in the region, which has been gripped by a conflict that the UN estimates has left 300,000 dead and 2.7 million displaced.

Khartoum wants Unamid to hand over five men and a woman from a camp for displaced Darfuris in Kalma who had sought the force's protection after clashes between the rebel Sudan Liberation Army and supporters of Qatari-hosted peace talks between rebels and the government.

Sudanese authorities have since blocked five international non-governmental organisations and UN agencies from reaching Kalma, one of the world's largest displaced persons camps during the dispute.