A Sudan Airways cargo plane smashed into a residential district of the Central African Republic capital of Bangui on Thursday killing around 20 people, witnesses said. The plane had been heading to Congo Republic but made a detour to Bangui because of technical problems and crashed short of the main airport, a source at regional air authority Asecna (Agency for the Safety of Air Navigation in Africa) said.

"We saw around 20 bodies in the wreckage of the plane. There was one survivor who was wounded and was carried away," said one witness.

He said he saw the markings of Sudan Airways on parts of the wreckage of the plane, which hit a market district.

It was not immediately clear if anyone had been killed on the ground.

Smoke was seen rising from the crash as worried residents hurried to the site to find out what happened and check on family and friends living in the area.

The crash is the latest in a string of air disasters on the continent -- the least safe to fly in last year according to figures from the Dutch-based Aviation Safety Network.

In Germany, relatives of the Russians killed in Monday night's mid-air collision have been visiting the crash site in the south and are preparing to help with the identification of the victims.

More than 130 relatives were flown into the town of Friedrichshafen, near the crash site, accompanied by two doctors and four psychologists.

Seventy-one people, many of them children from the Russian republic of Bashkortostan, were killed when a Tupolev passenger jet operated by Bashkirian Airlines collided with a Boeing cargo plane.

Crash investigators asked the parents of the 52 children and teenagers killed to bring with them their children's dental records and other items - such as unwashed clothes and hairbrushes - to aid DNA identification.

The cause of the crash remains unclear, but questions are being asked about Swiss air traffic control procedures after revelations that some equipment was switched off at the time of the crash and that one air traffic controller was on an unauthorized break.

And it has emerged that a report released a few days before the collision by the Swiss aviation safety body had raised questions about the quality of the controllers' radar system.

The disaster has prompted German Transport Minister Kurt Bodewig to renew calls for an integrated European Union air traffic control system.

The European Commission has already announced plans for an integrated system, but these are opposed by trade unions that fear job losses and say safety standards could be compromised.

MAP CAPTIONS

(Top) Central African Republic is one of the world's poorest countries, despite rich diamond mines. The country, located almost at the exact center of Africa, is slightly smaller than Texas, stretching from rainforest in the southwest to savannah in the north.
(Bottom) Relatives of the Russian victims of the Monday mid-air crash of a Russian airliner over Germany flew from Moscow on a Bashkirian Airlines Tupolev similar to the one in which their children died.