Police investigating the deaths of 26 elderly British tourists and their tour guide in a coach crash in South Africa yesterday say they believe that the driver was travelling well in excess of the speed limit when he careered off a sharply winding mountain road.

Doctors said most of the 10 survivors, who were in the last days of a two-week Thomas Cook tour of the country, were suffering from serious chest and limb injuries. At least two of them lost spouses.

One of the survivors, Leslie Dick, described how passengers screamed at the driver to stop after they were thrown into the middle of the bus as it swerved out of control, heading for the provincial town of Lyndenburg, in the north-east, near the Kruger national park.

"The road was very windy. All of a sudden it seemed to go out of control. Everyone started shouting 'stop'. The next thing the bus left the road. Then I remember I was sitting on the bank. There was lots of blood. I was afraid and disorientated because I could not see out of my right eye."

The coach rolled at least once down an embankment before coming to rest next to a tree. The roof was ripped off, the sides bent outwards and the seats crushed. Bodies and baggage were strewn across the hillside, some of the passengers landing 20 metres from the coach.

"I just saw bodies, they were lying all over," said a policeman. "We helped the injured where we could. People from town also came to help."

An ambulance driver said he had been sickened by the carnage. "I have never seen anything like that in my whole life. I saw people scattered all over. I saw one woman with her lower leg sliced off."

The party was travelling from the Sabi Sabi game reserve through the Long Tom pass, named after a large gun used by Afrikaner forces during the Boer war. Although the road is often shrouded in mist, police brigadier Mandla Mahlangu said driving conditions were good and no other vehicle was believed to be involved in the accident.

Police are waiting to speak to the driver, David Dube, who is in a critical condition in Lydenburg hospital.

"There's a tyre mark of 70 metres. It shows the brakes were very sharply applied. From this I think we can assume he was going at a very high speed. The limit on these roads is 60 kilometres an hour [37mph]. From the evidence, I think he was doing twice that," Brigadier Mahlangu said.

The coach operator, Springbok Atlas Tours, said it would not comment until the police investigation was complete. A Thomas Cook spokeswoman said the company was sending a five-strong team to mount an immediate investigation.

Thirty-seven people were on the coach. All but the tour guide and driver were British. Twenty-three died at the scene and four in hospital.

Most of the 10 survivors were described by Dr Susan Arstall at Lydenburg hospital as in a very serious condition and unable to speak to police. "They are in a very bad way. I don't think they are ready to see anyone yet," she said. But an official from the British high commission did visit some of the patients.

The high commission in Cape Town said that the victims came from across Britain. Those who died were from Essex, Norfolk, Cleveland, Surrey, Shropshire, Berkshire, West Yorkshire, Somerset, Northamptonshire, Middlesex, Devon, London and from Humberside. The injured are from West Sussex, Surrey, Humberside and Hertfordshire.

"Several married couples appear to be among the dead," a spokesman said.

A tour itinerary, headed "The Best of South Africa", found by police at the scene of the accident, showed that many of the tourists were booked to go on to visit the Victoria Falls.

President Thabo Mbeki issued a statement expressing his shock at the tragedy. "The deaths are not only a loss to the people of Britain, but South Africa has lost valuable ambassadors" who, by their choice of a holiday destination, had been "promoting the country as a tourist destination", Mr Mbeki's spokesman, Parks Mankahlana, said.

Yesterday's disaster was the fifth serious South African coach crash in a week. Between them they have claimed more than 60 lives and left more than 160 injured.

Opposition politicians and road safety groups have called for a government inquiry. The minister of transport, Dullah Omar, was said by his staff to be seeking an urgent meeting with coach operators, which would probably be held on Thursday.

Opposition politicians expressed concern at the likely impact of such accidents on tourism, which has already been badly bit by the high levels of violent crime in South Africa.

"We don't want our roads also to be questioned as another unsafe part of our country for tourists," said the opposition transport spokesman, Paul Swart.

Nearly 40,000 road accidents are reported in South Africa each year, claiming nearly 10,000 lives.