KHARTOUM - Armed men shot dead three World Food Programme (WFP) drivers in the southern Darfur region of Sudan, the U.N. agency said on Wednesday.

"WFP is deeply saddened and shocked by the killings of these brave men, who knew the dangers they were facing but continued to work tirelessly to alleviate suffering and bring food to the hungry in Darfur," said Kenro Oshidari, WFP country director.

The drivers, contracted to WFP from the Sudanese private Abbarci company, were killed in two incidents in South Darfur.

One attack on Tuesday killed two men near the towns of Haskanita and Muhajiriya where recent assaults on civilians and African Union peacekeepers left dozens of people dead.

The other driver was shot last Friday on the road between the South Darfur state capital Nyala and Darfur's main town el-Fasher, WFP said.

The world's largest aid operation helps some 4 million in Darfur, where 4-1/2 years of conflict has killed an estimated 200,000 people.

The recent upsurge in violence precedes peace talks due to start on Oct. 27 in Libya.

Fractious rebels are meeting in south Sudan's capital Juba to try to reach a unified position to ease negotiations.