New smart energy meters that the Government wants to be installed in millions of homes will leave householders vulnerable to cyber attacks, ministers have been warned.

The intelligence agency GCHQ is said to have raised concerns over the security of the meters, which could enable hackers to steal personal details and defraud consumers by tampering with their bills, it is alleged.

The Government wants every home in the country to have a smart meter, but only 8 million out of 27 million households have so far signed up to the £11 billion scheme.

They are designed to help consumers keep on top of their energy use and send meter readings electronically to suppliers, removing the need for visits to people’s houses to read their meters.

However, the rollout of a second generation of smart meters, known as SMETS 2, has been delayed because of worries about security.