The U.N. food agency is accusing Yemen's Houthi rebels of diverting food from the war-torn country's hungriest people and is threatening to suspend food aid unless they immediately implement registration and monitoring agreements.

World Food Program Executive Director David Beasley told the Security Council on Monday that the agency uncovered "serious evidence" of the diversion of food in the capital of Sanaa and other Houthi-controlled areas.

He said WFP has insisted on — and the Houthis finally agreed to — registration and biometric identification of beneficiaries and monitoring in December, but has faced roadblocks ever since in implementation.

Beasleu said if the agency doesn't receive assurances of action on the agreements "we will begin a phased suspension of food assistance, most likely towards the end of this week."