The Sudan government said rebels abducted the Sudanese nationals who were working for international groups.
UN officials are set to issue findings on efforts to stop the attacks that have exacerbated a humanitarian crisis.
The UN Security Council threatened to act if Sudan failed to disarm militias, blamed for killing civilians.
It called on the secretary general to report within 30 days after which it would reconsider what to do.
More than one million black Africans in Darfur have been driven from their homes, primarily by the pro-government Arab Janjaweed militia.