Rebels of the Sudan Liberation Movement took employees of the United Nations Development Programme (UNDP) as hostages on Saturday, said Sudanese State Minister for Foreign Affairs Najib al-Khair Abd al-Wahab.
The United Nations says fighting in Darfur, where a rebellion began a year ago, has displaced about one million people and that the threat of malnutrition and disease among refugees could cause a humanitarian crisis.
Abd al-Wahab said that the government is currently communicating with all sides. He condemned the incident and said he regretted the threats posed to the safety and security of employees of the UN and other aid agencies, particularly given the efforts they are exerting to restore stability in the Darfur region.
A UN official declined to comment on the report and Abd al-Wahab gave no further details. Spokesman for the rebels were not available to comment.
Rebels took up arms in Darfur against the government last year, accusing Khartoum of neglecting the remote area bordering Chad.
Around 158,000 refugee have fled to neighbouring Chad where the UN agency for refugees says many are at risk of attack by militias, and malnutrition and disease are spreading.