Sudanese air force bombers targeted the only hospital in the Nuba Mountains of war-torn South Kordofan, the former Catholic bishop for the area said on Monday.

The church-run Mother of Mercy Catholic Hospital was the victim of "deliberate targeting and bombing" last Thursday and Friday, Macram Max Gassis, the Kenya-based bishop emeritus of Sudan's El Obeid Diocese said in a statement.

He said the hospital serves more than 150,000 people annually.

Sudan's military spokesman could not be reached for comment.

Nuba Reports, a website based in South Kordofan, said nobody was killed in an initial bombing run by a Sukhoi jet on Thursday that sent hundreds of patients and visitors fleeing.

It said the blasts shattered windows in the home of the hospital's medical director.

The next day, bombs from an Antonov aircraft landed on a mountaintop, Nuba Reports said.

Almost three years of fighting between the government and Sudan People's Liberation Movement-North (SPLM-N) in South Kordofan and Blue Nile states has displaced or severely affected more than one million people, the United Nations says.

The alleged bombing occurred on the same day African Union-led peace talks between the government and rebels were suspended, tentatively to resume later in May.

As negotiations broke off, rebel delegation leader Yasir Arman accused the government of bombing SPLM-N areas "for more than 16 hours" during a major offensive.

The Kordofan-Blue Nile war has been fuelled by complaints among non-Arab groups of neglect and discrimination by the Arab-dominated regime.

International rights organisations have accused the Sudanese military of "indiscriminate" aerial attacks, while the government has said the rebels killed civilians during shellings of the South Kordofan state capital Kadugli.

Fighting over the previous two weeks in South Kordofan and Blue Nile affected about 16,500 people, according to figures cited by the UN's Office for the Coordination of Humanitarian Affairs said in its weekly bulletin on Thursday.