Nine people, including four Britons, have been killed and another 12 injured after a tourist bus crashed in the eastern part of South Africa, police said.

The crash occurred near the town of Piet Retief 285 kilometres (170 miles) east of Johannesburg.

There were 19 tourists, a guide and the driver on board on the bus which was returning to Johannesburg after a visit to a game park in KwaZulu-Natal province.

The bus was operated by Springbok Atlas, the same company which owned a bus which crashed in 1999 in the region, killing 26 British tourists and a tour guide.

The driver in that crash, near Lydenburg in Mpumalanga province, survived and was later found guilty of gross negligence.

Critical

According to Springbok Atlas, there were 10 Britons, six Canadians and three Germans on the bus.

The BBC's Johannesburg correspondent Hilary Andersson said that five of the injured were in a critical condition.

They are reported to have been airlifted to a hospital in Pretoria.

A spokesman for the British Foreign Office said that a consul and other staff were on their way to the scene to provide assistance.

Police are reporting that the driver lost control of the bus in heavy rain and it swerved and overturned.

Carol Scott, the chairwoman of Springbok Atlas, told the BBC that the driver of the 28-seater bus survived.

She said that he and the group's tour guide sustained serious head injuries in the crash.

Bus crashes are a frequent occurrence in South Africa.

Ms Scott told the BBC that Springbok Atlas had strengthened safety regulations in the wake of the 1999 crash and now all vehicles and drivers were closely monitored, with a tachograph fitted in every bus.

This equipment records the numbers of hours that drivers complete and the speed at which they drive.

The British Foreign Office has set up a hotline for anyone concerned about relatives or friends who may have been on the bus: 020 7008 0000