The United Nations food agency says insecurity in Sudan's war-ravaged Darfur region has forced it to cut deliveries of food aid by half.

The World Food Program said today Monday that bandits have hijacked 45 U.N.-contracted trucks in Darfur so far this year. It says 37 trucks remain missing and 23 drivers are unaccounted for.

The U.N. agency says the hijackings have made it hard to recruit new truck drivers. It says that as a result, food aid deliveries in Darfur have fallen to half the normal levels for this time of the year.

The WFP also warns it may shut down aid flights in Darfur by the end of this month because of a lack of funding for its air operation.

The WFP's representative in Sudan Kenro Oshidari called the situation "unprecedented," noting that the aid flights may be suspended when they are needed most because of banditry on the roads.

The U.N. agency says it costs $6.2 million per month to keep its airplanes and helicopters running in Darfur. The flights transport more than 8,000 aid workers every month to remote areas where they help with healthcare, water, sanitation and food relief.

International experts estimate that five years of conflict in Darfur have killed 200,000 people and driven more than two million others from their homes.

Some information for this report was provided by AFP, AP and Reuters.