In a release, WFP appealed for 87 million US dollars in food aid to cover needs in the refugee camps of eastern Chad until the end of next year.
It said contributions are urgently needed to ensure sufficient stocks are delivered to the camps ahead of the rainy season when road transport becomes all but impossible across most of the region.
"We need food now," said WFP Chad Country Director Stefano Porretti.
"With the rains only a matter of two or three months away, it is absolutely imperative that we move food to the places where it will be needed later this year. This process has already begun but is far from complete," Porretti implored.
"Once the rains begin, most of the camps become completely inaccessible by road. Getting supplies in place now will go a long way to avoid the necessity of expensive airlifts and air- drops further down the line. We need to get food here by road before it is too late," he said.
WFP said it faces a complex logistical challenge to get food to the camps in eastern Chad, where food sufficient for at least three months needs to be pre-positioned ahead of the rains.
The agency noted that the southern corridor from Douala in Cameroon would be virtually unusable during the rainy season, putting extra pressure on deliveries across the Sahara desert through Libya.
It said the northern corridor would become the sole lifeline to the camps while roads in the south remain impassable, adding that both routes require an average of four weeks for food to reach the camps.
The agency that it would, under a revision of its current emergency operation, also be assisting more than 150,000 Chadian nationals as well as providing for the possibility that an additional 150,000 people could cross the border from Darfur if the conflict continues.
Assessment missions towards the end of 2004 found that the health and nutritional condition of the refugees had largely improved since a survey carried out in June, it said.
However, the missions also concluded that in many cases the local population were facing severe difficulties in providing for themselves after a poor agricultural season and had become 'as vulnerable as the refugees'.
As a consequence, WFP said it was increasing its assistance to the local population by providing food to particularly vulnerable groups such as young children, pregnant women, nursing mothers and the elderly.
WFP has also initiated several schemes with its partners in which food is earned in return for work on projects to build local assets and infrastructure.
Among donors who have so far contributed to the WFP emergency operation for Sudanese refugees in Chad, the agency cited the US ($30 million), UK ($4.1 million), Germany ($3.6 million), France ($2.6 million), Canada ($ 2.5 million) and the European Community ($2.4 million).
Others are the Netherlands ($1.88 million), Switzerland ($1.61 million), Australia ($625,000), Norway ($593,000), Ireland ($530,000), Japan ($425,000), Finland ($249,000) and the United Arab Emirates ($116,000).