This would be the most dramatic move yet in the war that erupted earlier this year between retailers and the banks over the banks' sharp increases in processing charges.
Retailers are particularly angry over the increase in costs for the new-style debit cards, which take money directly from customers' current accounts and have been promoted by banks as a cheap and efficient method of payment for shops and customers alike.
The 1,550 petrol stations that sell BP are each considering whether to refuse to take Switch and Visa Delta debit cards for petrol sales of less than pounds 12.
BP's petrol retailing chain is the third-largest in the country and if the boycott is taken up widely it could be a considerable inconvenience for customers.
There are 12 million Switch cards and 11 million Visa Delta cards in circulation. Visa International says that in July 28 per cent of Visa Delta transactions were for petrol sales. BP says the average debit card transaction through its petrol stations is about pounds 13. Visa International says the average transaction value in garages is between pounds 12 and pounds 13.
BP says it is not itself running a campaign against the banks but will support any retailer who decides not to accept the cards for sales of less than pounds 12. The company has produced notices headlined 'Switch to cheque' for retailers to display.
Stations will put a warning sign up two weeks before they implement the boycott. At the end of this fortnight another notice will state: 'We are unable to accept Switch or Delta for payments of less than pounds 12 due to the increase in bank charges.
'We will be pleased to accept payment with a major credit card or cheque accompanied by a valid banker's card. We are sorry for any inconvenience. Please raise the matter with your bank.'
About 10 per cent of the 1,550 BP stations are owned and run directly by BP. Forty per cent are licensees, running BP-owned sites, and the other 50 per cent are independent operators. According to the petrol giant, individual petrol stations use a variety of high street banks to process their card and cheque payments.
But there have been increases across the board from the banks in the charges for processing card transactions. Credit card charges had risen by up to 15 per cent but debit card prices have doubled in some cases.
The cost of Switch transactions has risen from about 6p each to about 12p in the past three months. The charge for Visa Delta debit card transactions is now 17p, again about double the previous charge. Credit card transactions cost between 1.7 per cent and 2 per cent of the amount involved. The cost of processing cheques varies, depending on the pricing package each retailer has agreed with its payment-processing bank.
BP's spokesman said retailers were losing money on debit transactions below pounds 12.
He also said that the BP network had been one of the first retailing chains to take debit cards. The cards had been sold by the banks 'on the basis that it would help to reduce costs'.
BP now felt that the banks were not doing enough to contain their costs, especially the cost of plastic card fraud.
The spokesman added that BP's retailers were still negotiating with their banks over the debit card price increases and hoped for a settlement. He was aware of only a small number so far that had indicated they wanted to go ahead with the boycott.
Lloyds, Midland and Barclays banks all said they did little business with BP garages.
A spokesman for National Westminster defended his bank's price increases. He said that typically the charges were equivalent to 0.6 per cent to 1 per cent of a transaction. 'That is 10p to 12p on a pounds 12 transaction. We believe it is good value against other forms of payment.'
Royal Bank of Scotland said it believed that while credit cards may be cheaper for small transactions, under about pounds 5, Switch debit cards were cheaper on larger amounts.
Petrol retailers may find themselves at loggerheads with the banks that operate the Visa payment system if they refuse to accept debit cards. A spokeswoman for Visa International said that retailers' contracts obliged them to accept all Visa cards. 'That means that if they display the Visa logo they must accept all Visa cards and acceptance means acceptance, not refusing to take cards below a certain transaction size.'
Royal Bank of Scotland, one of the banks that founded the Switch system, said it believed retailers were breaching Switch rules by not accepting the cards.
Several large supermarket chains protested bitterly earlier this year over increases in plastic card processing costs and lodged complaints with the Office of Fair Trading, which is investigating.