A coach driver whose tour bus plunged down mountain killing 26 Britons - including four from Essex - may escape prosecution despite evidence that he caused the tragedy, it emerged today.

Detectives probing the crash at the treacherous Long Tom Pass in South Africa last September say mechanical failure has been ruled out but are doubtful whether gross negligence could be proved against father-of-five Titus Dube.

Supt Hannes Davel, the officer heading the inquiry, said Mr Dube's claim that the brakes on the four-year-old coach failed had now been dismissed but it was "50/50'' as to whether he would face charges.

The legal tussle came as holiday giant Thomas Cook released details of its own expert report into the crash - backing police findings that there was no fault with the coach which could have caused it to leave the road.

Victims and relatives of the dead warned that they feared the attempts to apportion blame meant the lessons of the accident - one of a series of fatal coach crashes in South Africa last year - could go unlearned.

The crash claimed the lives of an elderly couple from Purfleet and another couple from Colchester.

Mr Davel said his three-month investigation had focused on the braking system in the coach after Mr Dube, 41, told officers he had noticed a red warning light for the hydraulic brakes flashing intermittently days earlier.

But exhaustive testing on parts recovered from the wreckage, close to the town of Lydenburg in north-eastern South Africa, had found nothing wrong with the equipment and human error had been found as the cause, Mr Davel added.

Thomas Cook, which organised the tour the British group had taken with Johannesburg-based coach company Springbok Atlas, said its own inquiry by an engineering expert had pinpointed driver error as the cause. One 32-year-old woman, whose father was killed in the crash and her mother seriously injured, said: "What worries us is that no-one will end up taking the real blame and nothing will be done to ensure it doesn't happen again.

"There are all these inquiries lined up, seemingly ready to make a scapegoat of the driver, and in the meantime safety standards are not being changed while they wait for the process to be completed. It is bureaucracy gone mad."

The accident happened as the Springbok Atlas coach, manufactured in Britain and assembled in South Africa, was taking the British tour party from the Sabi Sabi private game reserve back to Johannesburg.

Witnesses reported the tour bus travelling at speed down the twisting mountain road before it left the road and overturned, ripping off the roof as the vehicle plunged 35ft and threw victims up to 200ft from the wreckage.

Mr Dube, who had been a driver for 20 years, said after the crash that the brakes had failed as he drove down the mountain.

His employers later confirmed that a fault had been reported in the days before the crash in a sensor linked to the gearbox but a mechanic had been dispatched and the problem solved.

A total of 26 Britons, many of them elderly, and a South African tour guide were killed in the tragedy.

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