It has become increasingly difficult to supply food aid to Darfur because of the worsening security situation, according to the World Food Programme.
Over 50 WFP trucks have been hijacked in the past 12 months
A senior WFP official told the BBC that more than 50 supply trucks have been hijacked there in the last year alone.
As many as 13 drivers are still missing, he said.
Fighting in the war-torn Sudanese region has increased recently, and some two million people there rely on the UN agency for their food supplies.
'Worse to come'
Speaking to BBC News, senior WFP official Paulo Mattei gave details of the losses his organisation had suffered in the last 12 months.
"That makes the delivery of food to this remote part of Sudan very difficult," he said.
And he warned that the situation will only worsen once the rainy season begins.
The WFP has not said who is behind the attacks on its convoys - there are numerous rebel groups and pro-government militia in the region.
Last Monday, the WFP warned that it may also be forced to halt its Humanitarian Air Service at the end of this month because of a lack of funding.
Progress on ending the violence in Darfur has been slow.
A joint UN-African Union peacekeeping force still has only 9,000 troops in the region out of a planned 26,000.