Credit card details sold on the black market could be worth over £57m, according to new research on the 'underground economy' released today by Symantec.

The security vendor monitored the internet chat rooms and forums where personal information stolen by hackers via Trojans, phishing attacks and other methods are bought and sold. Symantec found nearly 70,000 active advertisers selling compromised bank account and credit and debit card details, email accounts and pirated desktop games.

The goods were being sold for a total of more than £184m, although if these details were used to extract funds, the total worth of the credit cards alone could top £3.5bn, according to Symantec.

"This all points to the fact that cyber criminals are becoming increasingly well organised. While there might be an individual advertising, there are often gangs behind them," said Symantec chief scientist Guy Bunker.

"We cannot even guarantee to know all the underground servers in the world as they pop up and disappear on a regular basis."

Bunker argued that cross-governmental co-operation is needed to monitor and shut down these sites, many of which are supported unwittingly by hosting firms.

The EMEA region was found to be the second biggest region for hosting underground servers.