An investigation has been launched by Trading Standards Officers (TSOs) after thousands of motorists claimed they had been sold contaminated fuel.
Drivers said they had experienced problems after buying petrol from some service stations and supermarkets in the south of England, although there were reports it could have spread across the country.
Ian Hillier, from the Trading Standards Institute, said he understood there were around 75-100 complaints from people in the south east of England.
Independent oil company Greenergy told the BBC it was testing fuel supplied to Tesco and Morrisons to see if it was faulty.
Greenergy, which supplies ‘greener’ fuels, said its ‘extensive’ tests on the batch of fuel supplied to the supermarkets showed that it met industry standards but it was continuing its investigation.
The company added in a statement: ‘Greenergy has been made aware that some drivers using our fuels are experiencing some problems. We take this very seriously.’
Motorists say their vehicles have been juddering, misfiring and suffering a loss of power.
The UK Petroleum Industry Association, the trade association representing the nine main oil refining companies operating in the UK, stressed it was not a country-wide issue.
Tesco said it had done extensive tests on batches of fuel and had not found any link back to the store, but was working ‘urgently’ to find out what had happened.
In a statement, the store said: ‘We have had a number of reports from motorists who claim to be experiencing problems after filling up with fuel at Tesco forecourts and we are aware that customers of other supermarkets have also reported difficulties.
‘As soon as we were alerted to a potential problem we carried out extensive tests on current and past batches of unleaded fuel, including from some of the affected vehicles, and so far have not discovered any abnormalities or contamination whatsoever.
‘Whilst we cannot currently trace any problem back to Tesco fuel we will of course continue to urgently work with our supplier to identify what might be behind it.’
It added that if any problems with its fuel were discovered, the store would inform customers immediately and act quickly to put it right.
A spokesman for Morrisons said tests had found its petrol was not contaminated.
‘Morrisons suppliers test every batch of unleaded petrol to ensure that it meets British and European standards.
‘Having received a limited number of enquiries further tests were carried out.
‘These found no contamination and confirmed our unleaded petrol met the required standards.’
Joanne Barker, Senior Lawyer with Which? Legal Service, offers the following advice to drivers who believe they have been affected by the petrol that is purported to be contaminated.
‘At this stage, our advice would be to ensure that you keep proof of purchase, a sample of the petrol and any parts of your vehicle that need to be replaced.
‘It is also worth double checking the details of your car insurance and car warranty to see if you are covered for any work that needs to be carried out.
‘If it can be shown that the petrol was contaminated then the costs of repair can be reclaimed from the retailing garage.’
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