Computer security firm Symantec has put a price-tag on the size of the underground digital economy - and it's well over £4.5 billion.

That's the total estimated value of all the credit cards and bank accounts it found for sale by criminal hackers on the servers it tracked for a period of 12 months.

Credit card information was the most advertised category on the underground economy, accounting for nearly a third of the total. Stolen credit card numbers sell for as little as 7 pence, with an average claimed credit card limit of over £2,650.

If all the advertised cards were maxed out, they would earn crims a bailout-tastic £3.5 billion.

No recession in online fraud

Bank accounts made up a further 20 per cent of products for sale, ranging in price from £6.50 to £650, but holding an average balance of £26,700 - in itself pretty surprising given the state of the economy.

"Today's cybercriminals are thriving off of information they are gathering without permission from consumers and businesses," said Stephen Trilling, Vice President at Symantec.

"As these individuals and groups continue to devise new tools and techniques to defraud legitimate users around the globe, protection and mitigation against such attacks must become an international priority."

Symantec found the largest number of criminal servers in North America (hosting nearly half the hackers), followed by Europe with 38 per cent, Asia with 12 percent and finally those law-abiding Latin American folk with just 5 percent.

The geographical locations of underground economy servers are apparently constantly changing to evade detection.