FORMER Top Gear star Richard Hammond has broken his silence after surviving a horrific car accident in the Swiss mountains.

Hammond, 47, was filming his Amazon TV show The Grand Tour when his electric supercar left a mountain road in St Gallen in northeastern Switzerland and burst into flames.

He was airlifted to hospital but tests showed he had escaped the high-speed crash and ensuing fireball with only a fractured knee.

Hammond reassured fans with a video appearance from his hospital bed on Sunday.

The video was broadcast by Drive Tribe under the jokey title: “I’m not dead.”

In the video Mr Hammond confirmed he would require knee surgery.

“I would like to thank all of the medical professionals who got me by air ambulance from the crash to the hospital and who have dealt with me ever since,” he said. Hammond also apologised to his wife and two daughters.

Co-star Jeremy Clarkson tweeted about the accident, saying: “It was the biggest crash I have ever seen and the most frightening but incredibly and thankfully, Richard seems to be mostly okay.’’

In an article on the DriveTribe website, Clarkson confirmed that Hammond had been driving the car for four days prior to the accident.

“He knew the car well, he knew how fast it was, and he knew how to handle it in the bends,” he said.

The former Top Gear presenter revealed he thought Hammond was dead when he arrived at the scene shortly after the accident.

“It was obvious from the skid marks what had happened. He’d lost it somehow on the final bend after the finishing line and had plummeted down one bank onto a road lower down the hill, which had caused his car to flip.”

Clarkson said he stood with his knees “turning to jelly” until a member of the show’s security detail revealed that Hammond was ok - by winking at him.

“For all the rest, all the details, and who knows, another book; well I’ll leave that up to Hammond when the lucky sod feels up to it,” Clarkson stated.

Video from @richardhammond direct from his hospital bed: https://t.co/lAHxpFnQTP — The Grand Tour (@thegrandtour) June 11, 2017

Photographs showed a burned-out wreck of a car resting on its roof.

Hammond was critically injured in a high-speed crash back in 2006 which left him in a coma for several weeks but recovered and went on to build an international following with Top Gear before following Clarkson when he was sacked from the show in 2015.

The accident is thought to have happened on Saturday afternoon.

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St Gallen police spokesman Gian Andrea Rezzoli told Swiss newspaper 20 Minuten that the driver of the car was taken by air ambulance to hospital and the fire was extinguished by firefighters.

Hammond was conscious and got himself out of the car before it was engulfed in flames.

The Grand Tour confirmed Hammond was completing the Hemburg Hill Climb in Switzerland in a Romac Concept One, an electric supercar built in Croatia, when the accident happened.

“Richard was conscious and talking and climbed out of the vehicle himself before it burst into flames,’’ the show said in a statement.

“No-one else was in the car …and we’d like to thank the paramedics on site for their swift response.”

“The cause of the crash is unknown and is being investigated.’’

A spokesman for the Hemberg race organisers, Marco Moser, said the demonstration runs are intended to showcase unusual vehicles and offer spectators “something special”.

“No accident is nice for us,” Moser said.

“But accidents do happen in high-risk sports. Of course when a car goes up in flames, then there’s quite a bit more adrenaline.”

“We’re happy that Richard Hammond is doing well, under the circumstances,” he added.