Harvest Energy, the independent blender and fuel wholesaler at the centre of last month’s contaminated fuel furore, is putting steps in place to ensure more rigorous fuel testing procedures, as it seeks to restore confidence in the brand.

The company is also proposing to the relevant European and British Standards organisations - via its trade body the Association of UK Oil Independents - for the inclusion of a silicon test within the BS EN 228 standard for unleaded petrol.

Harvest’s head of sales, Simon Davis, revealed that initial investigations had shown unusually high levels of silicon in four petrol storage tanks at the oil terminal owned by Vopak at West Thurrock, Essex. Fuel blended from these tanks was supplied to various petrol retailers - mainly supermarkets - in the south east, causing mayhem as many thousands of motorists broke down.

"We are putting steps in place to ensure more rigorous testing of our fuels - which do reach the European and British specification, but the specification does not include a test for silicon. We are now testing for silicon as a matter of course. But the more we’ve dug into the problem, the more we have become aware of other elements that may not currently be included in BS EN 228 specification and which may have an adverse impact on vehicle performance. We are now aware of serious problems occuring in other parts of the world that have not been publicised."

Industry estimates of the number of cars affected range from 5,000 to 20,000 - which could therefore cost up to £10m to rectify - with insurance companies of all the parties involved engaged in sorting through the various claims for the next few months.

Ian Hillier, petroleum spokesman for the Trading Standards Institute, said the focus now was on helping affected customers to pursue compensation claims. "The supermarkets are paying an average of £400-£500 per car," he said. "The issue has now become a chain of compensation claims, and having accepted responsibility, Harvest will have to pay out to the affected companies."