U.N. sources say Yemen's Houthi rebels have banned over 35 U.N. and international agencies and relief groups from working in the territory under their control, citing lack of proper clearance.

The sources told The Associated Press that negotiations are underway, without providing further details. They spoke on condition of anonymity because they weren't authorized to brief the press.

A leaked document posted on Twitter by the Yemeni Embassy in Washington, operated by the government, showed a list of 35 agencies, including the World Health Organization, the U.N. children's agency and Oxfam.

The document, purportedly signed by a Houthi-allied deputy health minister, orders officials to "ban them from movement in and to governorates," because they work "unilaterally."

Yemen's civil war has killed 10,000 people and displaced 2 million.