A British hacker is being sought by US authorities over a hack attack on web shops.

Lee Graham Walker, along with German Axel Gembe, are being accused of involvement in attacking websites of series of web retailers.

In particular, they are being connected with what are known as Denial of Service attacks, which effectively knock web shops offline.

The duo are believed to be the tech masterminds behind one such case when two shops that sell digital video recorders and TV satellite equipment went offline.

Miami-based Rapid Satellite and Los Angeles-based Weaknees were forced offline for a fortnight in October 2003.

Recovery from the attacks is reputed to have cost one of the shops $200,000.

Two men have already bee charged - one Paul Ashley and one Jay Echouafni, who ran a rival e-shop to the two that were knocked offline.

But now the FBI says that it was Brit Walker who actually ran the network of hijacked home computers, or botnet, that bombarded the web shops with bogus data in a bid to overwhelm them.

And Gembe created the virus, called Agobot.

The latter was tried for the Agobot in 2004, and received a probationary sentence.

Both men are now claimed to be "at large" but, if caught, could face a 15 year prison sentence.