They were supposed to be impossible to forge – but fake new pound coins are already in circulation.

Just one month after the 12-sided coin was released to the public, a forgery has already been found.

That’s according to a charity worker in Surrey, The Mirror reports.

The man, who did not wish to be named, said the fake was heavier, the Queen’s head was positioned further to the left, the edge was more rounded.

The new £1 coin

The ‘fake’ also lacked the hologram found on genuine coins and detail was missing from the head of the thistle.

The new coin is meant to feature a hologram at the bottom which shows a ‘£’ symbol and the number one depending on the light.

There is also a secret high-security feature built into the coin designed to protect it from counterfeiting.

The new pounds were introduced amid reports that as many as one in every 30 old pound coins were counterfeit.

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Hundreds of ‘trial piece’ coins were given to retailers to help calibrate or upgrade coin-handling equipment ahead of the real coin’s introduction on March 28.

They are not legal tender and cannot be used in shops – although they are fetching decent prices on eBay.co.uk.

In a statement, the Royal Mint said it was unlikely the coin was counterfeit, however it could not guarantee this without examining the coin first.