A British citizen is one of two men charged with launching hack attacks against retail sites in the US.

Lee Graham Walker, of Bleys Bolton, England, was charged with one count of conspiracy and one of intentionally damaging a computer system, according to the FBI.

Also charged in the case is Axel Gembe, a German resident. If convicted, the men could each face up to 15 years in prison.

According to the FBI, 24 year-old Walker and 25 year-old Gembe were part of a larger group which launched two distributed denial-of-service (DDoS) attacks against two companies in 2003.

Heading the plot was Jay Echouafni, who owned Orbit Communications Corporation. Authorities allege that Echoufani and associate Paul Ashley hired Walker and Gembe to launch a series of attacks on two of Echoufani's competitors.

Authorities allege that the pair used a worm developed by Gembe to compromise a network of machines to flood the sites with traffic and send them offline.

The DDoS attacks crippled both sites for two weeks and caused hundreds of thousands of dollars in damage, the FBI claims.

Ashley has since pleaded guilty and has served a two-year prison sentence in Ohio. Echoufani is on the run and is considered a 'fugitive' by the FBI.