Hackers steal details from 40 million credit cards in 'world's biggest ever' identity theft

Eleven members of the gang were indicted in Boston over the theft of more than 40million credit and debit card numbers.

Gang members who have been charged by the U.S. Justice Department include three U.S. citizens and others from Estonia, Ukraine, Belarus and China.

Scam: Thieves used laptops to gain wireless access to millions of card details stored by major retailers

They set up programs that captured card numbers, passwords and account information.

The technological theft is thought to have been the biggest of its kind.

U. S. Attorney General Michael Mukasey said the value of the fraud conducted using the stolen card detail was 'impossible to quantify at this point'.

He said: 'They used sophisticated computer hacking techniques that would allow them to breach security systems and install programs that gathered enormous quantities of personal financial data, which they then allegedly either sold to others or used themselves.

'And in total, they caused widespread losses by banks, retailers, and consumers.'

A lawyer working on the case said most of the victims were in the U.S., although officials still haven't identified all the people who have had a card number stolen.

US Attorney Michael J. Sullivan said the alleged thieves weren't computer geniuses. They were opportunists who used a technique called 'wardriving', which involved cruising through different areas with a laptop and looking for accessible wireless internet signals.

Once they located a vulnerable network, they installed so-called 'sniffer programs' that captured credit and debit card numbers as they moved through a retailer's processing networks.

The information was stored on two servers in Ukraine and Latvia  -  one with more than 25million credit and debit card numbers and another with more than 16million numbers.

However, court papers suggest that the number of cards affected could have topped 100million.