Security experts Symantec reckon online fraudsters are making a whooping £3.3bn out of unsuspecting web surfers.

After studying the internet's underground economy for a year, Symantec believes this is the figure online criminals are making out of selling credit card numbers and bank details.

Credit card numbers made up 31% of the illicit goods being haggled over on the internet, while bank details came in second at 20%.

The BBC says: "The $5.3bn figure was reached by multiplying the average amount of fraud perpetrated on a stolen card, $350 (£234), by the many millions Symantec observed being offered for sale".

Symantec added that while some of the card details being sold were for cards that had been cancelled or the bank accounts sold, the figures are still accurate: "These figures are indicative of the value of the underground economy and the potential worth of the market".

But who are these fraudsters?

Symantec says that it is the Russian and Eastern European gangs that are the most organised but there are criminals everywhere, and they will work together to make as much cash as possible.

"Symantec research indicates that there is a certain amount of collaboration and organisation occurring on these forums, especially at the administrative level", Symantec said.