Sudan has ordered two senior United Nations officials to leave, a UN spokesman said Thursday, after a recent spike in tensions between Khartoum and the peacekeeping mission in Darfur.

   The UN resident coordinator and humanitarian coordinator Ali Zaatari and the UN Development Programme country director Yvonne Helle were asked by the government to leave, a UN staffer said.

   Spokesman Stephane Dujarric said the UN has protested the expulsions.

   "The UN has filed a protest with the government of Sudan following their decision to request the departure of two senior UN officials from the country," Dujarric told AFP.

   It was unclear clear why the UN officials were asked to leave, or when they would have to exit the country.

   The UN staffer, who spoke on condition of anonymity, declined to provide further details.

   The UNDP and Sudanese foreign ministry did not respond to requests for comment.

   Zaatari, a Jordanian national, had been in Sudan for nearly two years, and Helle, who is from the Netherlands, had spent about a year heading the UNDP's office in the country.

   The expulsions come as Sudan's government is locked in a dispute with the hybrid UN-African union mission in Darfur.

   Ties between the two have frayed over Khartoum's anger at UNAMID's attempts to investigate a report that government troops raped 200 women and girls in a village in the war-torn western region on October 31.

   Sudan demanded UNAMID form an "exit strategy" from Darfur, where they have been deployed since 2007 and ordered it to shut a human rights office in Khartoum last month.

   Zaatari and Helle's expulsion are the latest in a string of incidents with foreign aid and humanitarian workers in Sudan.

   In April, the government told the American chief of the UN Population Fund in Sudan to leave for "interfering" in internal affairs.

   The UN and international NGOs provide aid to some of the areas of Sudan worst affected by the conflicts wracking its peripheries.

   The government is battling an insurgency in Blue Nile and South Kordofan, as well as a protracted conflict in Darfur.

   Ethnic insurgents rebelled against Khartoum in 2003 complaining they were being marginalized, and in the intervening 11 years, the UN says some 300,000 people have been killed and two million displaced. (AFP)