Invented in Britain but only available in New York, the anti-terror scanner that could prevent another 7/7

The Government is under fire for failing to invest in ground-breaking technology that could prevent a repeat of the July 7 terror attacks in London.

Fifty-two people died when suicide bombers detonated their devices on a bus and three Tube trains in 2005.

Now Qinetiq, a British defence company until recently owned by the Government, has developed sophisticated scanners that can spot terrorists carrying hidden bombs and weapons in crowded stations.

Despite the fears of new attacks, the Government has declined to buy the devices - but they are being installed in New York.

The so-called SPO scanners monitor natural radiation emitted by the human body. Objects made of metal, plastic or ceramics - such as a gun or a bomb - that are hidden in a person's clothes block this radiation.

Such "cold spots" are picked up by the SPO, which uses sophisticated software to identify suspicious objects and alert an operator. Individuals can then be searched.

The equipment, which can monitor people in crowds up to 60 feet away, was first developed to help helicopter pilots fly in low visibility.

Twelve scanners have been sold to the US Transportation Security Administration (TSA) to protect New York's Staten Island ferry ports, which are used by 60,000 people a day to commute to work in Manhattan.

The TSA is considering buying more devices to cover the city's Subway network and Grand Central Station.

Qinetiq was formed from the Defence Evaluation and Research Agency (DERA), part of the Ministry of Defence. The Government continued to control the company, holding a so-called "golden share", but sold its stake in 2002.

Last night senior Conservatives attacked Labour for not investing in the technology, which has the potential to save hundreds of lives.

Tory Defence spokesman Gerald Howarth said: "This Government has consistently failed to invest in technology.

"Gordon Brown sold Qinetiq to make a quick buck. He has never been interested in defence.

"He and his Government are now more interested in locking people up without charge than investing in British technology that might protect us."

Edward Leigh, Tory chairman of the Commons Public Accounts Committee, which has been investigating accusations that Qinetiq was sold off too cheaply, said: "British taxpayers are losing out on two fronts.

"They are not being protected by the technology produced by this company, which once worked purely in the national interest, and they were short-changed when the firm was sold off."

Asked whether the Government had made approaches to install the SPO system on transport networks, a Qinetiq spokesman said: "We are in regular discussions with Government departments and have conducted trials of the SPO system for a number of different organisations in the UK."

A Department for Transport spokesman said it was "aware of the new devices and was monitoring their effectiveness".

But he said no decision had been taken on whether to buy the scanners or to put them in vulnerable stations.