Gunmen killed at least 20 civilians including children in Sudan's war-torn Darfur as they returned to their fields for the first time in years, a witness and a tribal chief said Saturday.

Twenty people were also wounded in the attack in Aboudos, south of Nyala, capital of South Darfur province, tribal chief Ibrahim Ahmad told AFP.

Darfur has been devastated since 2003 by a conflict that has killed 300,000 people and displaced 2.5 million others, according to the UN. 

Those killed in Friday's attack were mostly displaced farmers who had returned to their fields under a government-sponsored deal struck two months between "the original landowners and those who took their fields," Ahmad said. 

AFP