TESCO and Morrissons have moved to stop supplies of suspect petrol.

Morrisons has stopped selling unleaded at 41 outlets supplied by the Vopak depot in West Thurrock.

Tesco is emptying its unleaded petrol tanks at 150 outlets and will refill them with new stocks.

Tesco's own tests have found silicon in its fuel.

A company statement said: "These tests show evidence of some significant silicon contamination in samples taken from unleaded petrol released from the Vopak terminal around 10 days ago.

"We believe this to be the source of contamination subsequently experienced by some customers in the south-east of England."

Hundreds of motorists across south Essex have been turning up at garages with faltering cars, fearing they have filled up with contaminated petrol.

Since the fuel story broke, Toomey Chevrolet, in Westmayne, Basildon, has looked at more than 100 cars suffering problems with O2 sensors, which monitor the fuel mix in modern engines.

Company director Barry Ives, 44, said: "We're replacing sensors like they've gone out of fashion.

"The manufacturers have started to run out of the parts, which indicates how serious the problem is."

Over the same period, Basildon Motoring Centre, in Long Riding, Basildon, has seen more than 60 cars.

Mark Bottle, 46, who has supplied car parts for 20 years, says he has never seen anything like it: "It's like an epidemic. The phones first went into meltdown last Monday.

"We were inundated with calls from motorists whose engine lights had come on."

The cost of repairing the damage has ranged from £500 to £1,000.

Ian Clements, 55, service advisor at the Kia garage, in Chase Road, Southend, said he had been asked to check three cars so far.

He added: "I've been in the car industry for 40 years and this is the most serious problem we've had.

"Car owners who have experienced problems have been deeply affected.

"Some women have been driving on their own and their car has spluttered to a halt.

"We've also seen mums who had their kids in the back. Losing control of their vehicle was terrifying for them."

The petrol is claimed to have come from Greenergy, a company which stores fuel at the Vopak depot, in Burnley Road, West Thurrock.

Thurrock Trading standards officials have also launched an investigation. They will assess the extent of the complaints and liaise with major fuel suppliers based in the borough, in an effort to pinpoint the cause and the source of the problem.

Couple's £1,000 bill

Louise Caten and partner David Jon were stunned by the news contaminated fuel has landed them with a £1,000 repair bill.

Miss Caten, 41, of Herbert Road, Shoebury, first noticed a problem with the couple's Citroen Xsara Picasso, after filling up on petrol at Asda, in Ness Road, Shoebury.

She couldn't understand what made the car jolt and judder, but thought nothing of it, until she heard in the news a contaminated batch of petrol might be responsible for faults in cars across south-eastern England.

Mum-of-three Miss Caton said: "I was sitting at some traffic lights in Leigh and the car was making an unusual whirring sound, which I thought was odd.

"The car seemed to have no power when I tried to turn right. Then it shot forward really fast and then stopped again, in mid-turn.

"It was really frightening, because cars were driving straight towards me."

She took the car to Bridge Garage, in Ness Road, Shoebury, after Miss Caten's partner, David Jon, had similar experiences, driving the Citroen people-carrier.

Mr Jon, 36, said: "I pulled out onto a roundabout and the car stalled.

"The steering locked, the acceleration failed and the car just rolled forward.Other cars had to slam on their brakes, so they wouldn't crash into me."

Now the couple has been told is it going to cost £1,000 to replace the faulty engine management computer, a component which regulates petrol flow to the engine.

Mr Jon added: "The garage said it believed the problem was caused by contaminated petrol and would back us up.

"When I complained to the Asda garage, it said it had been inundated with calls, so is aware of the problem."