The founder of online gambling company BetOnSports PLC has been sentenced to more than four years in prison after agreeing to forfeit more than 43 million dollars.

Gary Kaplan, 50, pleaded guilty in August to racketeering charges. He was sentenced by a US District Court judge in St Louis, Missouri, on Monday to 51 months in prison followed by three years of supervised release.

Judge Carol Jackson also ordered Kaplan, who dropped out of high school, to obtain a high school equivalency degree.

In his plea deal, Kaplan agreed to forfeit 43.65 million dollars in "criminal proceeds" from the online gambling operation.

David Carruthers, 52, the British former chief executive of London-listed BetonSports who was arrested in Texas in July 2006, has also pleaded guilty to racketeering charges and is scheduled to be sentenced in January.

According to the Justice Department, Carruthers was hired in June 2000 by Kaplan to become CEO of Costa Rica-based BetonSports.

Most publicly traded British gaming firms have quit the US market following passage of a US law that bars banks and credit card firms from processing payments linked to online gambling.

The United States has stepped up a crackdown on Internet gambling, claiming that even sites operating from offshore violate US laws by taking wagers from Americans.