The founder of the defunct British online gambling firm BetOnSports pleaded guilty in U.S. court on Friday and agreed to forfeit more than $43 million in criminal proceeds, the Justice Department said.

It said Gary Kaplan, 50, who founded the high-profile early player in offshore Internet sports gambling, pleaded guilty to charges of conspiring to violate the federal racketeering and other U.S. laws.

Kaplan, who transferred a week ago from a Swiss bank account the $43,650,000 he had agreed to forfeit, entered his plea in U.S. District Court in St. Louis.

If the judge accepts the terms of the plea deal, Kaplan will be sentenced to a prison term of 41 to 51 months, the Justice Department said.

Kaplan's sentencing has been set for October 27. He has been in custody without a bond set since his arrest in March of 2007.

BetOnSports ceased operations in 2006, and customers lost between $7 million and $20 million, the Justice Department has said.

Kaplan admitted in court that beginning in the mid to late 1990s, he set up business entities offshore in Aruba, Antigua and eventually Costa Rica to provide betting services to U.S. residents through Internet Web sites and toll-free telephone numbers.

Some of his Web servers were located in Miami and U.S. customers placed wagers over U.S. telephone lines.

Kaplan in mid-2004 made a successful public offering of the stock of BetOnSports on the London Stock Exchange's AIM market that netted him over $100 million, the Justice Department said.

John Gillies, the FBI's special agent in charge in St. Louis, said: Today's guilty plea should have a lasting effect because Kaplan was not only the founder of BetOnSports, he was also one of the pioneers of illegal online gambling.

(Reporting by James Vicini; editing by Todd Eastham)