A record number of fake £1 coins could result in the Royal Mint scrapping and then reissuing the coin to restore faith in their authenticity.

The alarming prospect of a reissue came to light in a Parliamentary answer supplied by Justine Greening, Economic Secretary to the Treasury, to MP Andrew Rosindell. The answer has been reported by the Daily Telegraph newspaper.

Rosindell said the rising numbers was a 'genuine matter for concern'.

The Treasury statement said that there are £41m fake £1 coins in Britain – this means that one in every 36 in circulation is a worthless fake.

The level of fake coins is getting worse. This is Money reported in September 2008 that one in 50 was a fake and last year Treasury figures suggested one in 40 were fake.

Currency experts believe criminal gangs are mass-producing the coins using specialised machinery.

The level of fakes are so high that there is now a serious risk that consumer confidence in Britain's most popular coin could suffer as a result.

Small shopkeepers have the most at stake from accepting a fake £1 coin as they are not refunded by the bank if they send fake coins from their till.

Mr Rossindell added: 'This has a huge effect on confidence in our currency. Clearly the one pound coin is something the Royal Mint needs to reconsider. Even one in a hundred fake coins is too many.'

As more sophisticated mechanisms come into use to make the fake coins, they are becoming increasingly hard to spot.

We've all had that irritating experience of trying to get a parking metre or vending machine to accept a £1 coin. If they are rejected, they are usually a fake, as the machines contain devices to monitor whether the metal composition of the coins are correct.

However, the fakes are becoming so good that around half of these are beginning to pass these tests.

Soft drink and snack machines take £1.6bn of coins every year, and Jonathan Hilder, the chief exectuive of the Automatic Vending Association of Britain, told the Telegraph: 'If fakes continue to rise, re-minting will have to become an option.'

Other countries have had to re-issue coins due to counterfeit problems. The 5 rand coin in 2004 was re-issued after places started to refuse to accept them. Over there, 2% of the counterfeits were fake. At the moment, an estimated 2.8% of British £1 coins are fake.

Robert Matthews, who formerly tested coins as the Queen's Assay Master, said: 'If the number of fakes keeps increasing at this rate, there will have to come a point when the Treasury makes the decision whether to remint or not.'

Mr Matthews added the number of fakes in other currencies is far lower. Only 0.1% of euros - some 10m - are fakes, according to research in 2006.

The Royal Mint insisted that the number of fake pound coins is low considering the numbers in use. There are thought to be more than 1.45bn in circulation.

The pound coin, made from a mixture of copper, zinc and nickel, was introduced in April 1983 to replace the £1 note.