Kenyan media said the number of dead could rise to 100. Police said at least 22 people had survived and were in hospital.

A bus conductor of one of the buses told a BBC reporter in hospital that the buses had been trying to overtake for some 20km before the accident in a race to get to the coastal town of Malindi first to pick up passengers.

The accident happened on a bridge over the Sabaki River near the Malindi, 96 km (60 miles) north of Mombasa at about 1830 local time (1530GMT) on Sunday.

River plunge

One of the buses reportedly swerved to avoid another vehicle carrying tourists that had stopped on the bridge and hit the other bus from behind. They both plunged into the flooded river below.

Divers worked in the river as people watched from a bridge

A Kenyan naval rescue team was sent to retrieve bodies from the sunken buses.

News agency reports from the area say the rescue effort has been suspended until heavy lifting equipment can be brought to the site.

Two cranes have reportedly failed to lift the sunken vehicles.

The Daily Nation newspaper said strong river currents and a moonless night hampered initial rescue efforts by more than 100 volunteers as they worked by the headlights from a truck.

'Horrific'

There was also a danger from hippos, which come out to feed at night and can attack anything that interferes with this.

The East African Standard quoted a witness, Mama Veronica, as saying: "The scene was horrific. The guard rails had been crushed flat and bodies were falling into the water."

On 29 March last year 101 people were killed when two overcrowded buses collided and burst into flames at Kapkatunga 300km (185 miles) west of Nairobi.

That accident occurred when one of the bus drivers lost control while negotiating a sharp corner and hit the other bus, police said.