NAIROBI, Kenya (AP) _ Trying to avert a looming famine in war-ridden southern Sudan, the United Nations said Thursday it sent a seven-barge convoy down the Nile with enough food for tens of thousands.

The convoy, however, will not be able to reach Bahr el-Ghazal province, where up to 50,000 people are in immediate danger of starvation, said Michele Quintaglie, spokeswoman for the World Food Program. The province's waterways, shrunken by the blazing sun, are no longer navigable by barge.

The World Food Program said the convoy is making a six-week trip from the southern port of Malakal to drop off food and medicine at 34 villages in both rebel- and government-held territories.

Rebels have fought since 1983 for greater autonomy from the Islamic-dominated government for southerners, mainly Christians and animists. More than 1.5 million Sudanese have died in the fighting and consequent famines.

A surge in fighting coupled with persistent drought has caused 700,000 southerners to miss their harvests this year. Of those, 350,000 are in Bahr el-Ghazal province, where international food aid can be delivered only by air.

British International Development Secretary Clare Short on Wednesday accused the government of blocking emergency aid to southerners because it feared aid would strengthen the rebels.

On Thursday, the Sudanese government denied the charge and accused the rebels of impeding assistance in Bahr el-Ghazal.

The World Food Program said the barge convoy was carrying 2,040 tons of cereals and beans, most of which will go to Juba, the southernmost government-held city and a rebel target for years. Juba's population has swollen with the influx of people who fled their homes.

The convoy is the first of three planned trips to Juba this year. Similar operations are planned for the population along the Sobat, Zerat and Bentiu river corridors, WFP said in a press release.