There were 40 passengers and five crew members on board the South Supreme Airlines plane that had taken off from the capital Juba, said the airline's manager Gabriel Ngang.

State Information Minister Bona Gaudensio said an ambulance had brought the passengers from the airport to the hospital, and most of them were released shortly after.

"We had 37 passengers taken to the hospital and so after they were given first aid we have released 31 of them and we will release the rest tomorrow," Gaudensio told AFP.

He could not account for the remaining eight people who had been on board, but claimed there were no deaths in the accident.

Paul Charles, an engineer at Wau airport, and local radio journalist Lawrence Yunisen both told AFP that some passengers -- not counted among the injured -- had managed to flee the burning plane unscathed.

Charles said the weather in the region had not been good when the plane attempted to land.

"Visibility was not good up to now and (the plane) was landing from the east to west, then it just crashed (off) the runway. The pilot I think was not seeing the runway well," he said.

"Some of the people got out by themselves, some of them were pulled. Only the back part of the plane remains but the rest was burned," he added.

Video images obtained by AFP showed firefighters battling to put out the blaze as thick black smoke billowed from the aircraft. The plane was completely burned out except for the tail, which clearly displayed the insignia of South Supreme Airlines, a local carrier.

In November 2015, 36 people were killed when a Soviet-era Antonov plane crashed just after take-off from Juba. Two survivors were pulled from the twisted metal hulk but one later died.

South Sudan has been gripped by civil war since 2013, and the country is also in the midst of a "man-made" famine due to the conflict.