Claims arising out of the faulty fuel fiasco could spiral to millions of pounds, a leading lawyer warned this week.

Thousands of motors are believed to have been affected by a batch of defective petrol which caused cars to break down last week. The source of the petrol was traced to supermarkets Tesco, Morrisons, Asda and Total, across the south.

Law firm, Marishal Thompson, said 3,500 people had signed up to a website with the aim of claiming compensation from the super-market giants.

A decision about whether to bring a class actions claim against the suppliers of the faulty fuel was being take as Insurance Times went to press.

Tesco and Morrisons have admitted liability, whilst fuel suppliers, Harvest Energy, accepted that it had supplied contaminated fuel. A Harvest Energy spokesman said: "We are in discussions with retailers about compensation, although it is too early to say how many claims there will be."

Harvest Energy said its product liability insurer was AIG, and stock was insured at Lloyd's.