While supplies of some commodities such as cereals, which form the major part of general food-distribution rations, have not yet been affected, complete breaks in the supply of other rations are now imminent, WFP said in statement released on Friday.

"Ration cuts are a last resort, but we simply have no alternative," said Bradley Guerrant, WFP Sudan deputy country director. "We are cutting amounts of these three items in general food distributions so that we can keep some supplies going for longer. And we need to set aside stocks for the highest priority groups.

"In particular, we are earmarking remaining sugar for feeding centres across Sudan to make sure that malnourished children and pregnant and lactating mothers get this vital part of their diet," he added.

Towards the end of February, WFP said it had received only 4 percent of the US $746 million it needed to feed more than six million people across Sudan in 2006. Even now, WFP has received only 15 percent of its target, leaving the agency critically short of funds.

Another $234 million is needed to allow WFP to ensure supplies of food aid continue in the critical months ahead.

"While the latest donation from the United States - which brings their total contribution to $114 million - is extremely welcome, we are urgently appealing for more cash so that we can continue to move food stocks into place in Sudan, in advance of the rainy season," said Guerrant.

Roads become impassable during the rainy season, which coincides with the "hunger gap", or the period before the harvest, when needs peak. "If we cannot truck in stocks before the rains start, we are forced to rely on much more expensive airdrops and airlifts," he added.

Among those receiving food assistance from WFP and its partners in Sudan are displaced people in camps across Darfur and returnees, who, in the wake of last year's Comprehensive Peace Agreement, are now trekking back home to southern Sudan.