(Bloomberg) -- Betonsports Plc Chief Executive Officer David Carruthers was indicted by a federal grand jury on charges of racketeering conspiracy in connection with a U.S. gambling probe.

The London-based Web gambling company was also charged, along with its founder, Gary Stephen Kaplan, the Justice Department said. The indictment, issued June 1 by a federal grand jury in Missouri and unsealed today, charges nine other people and three additional companies.

``Illegal commercial gambling across state and international borders is a crime,'' Catherine Hanaway, U.S. attorney in St. Louis, said in a statement. ``This indictment is but one step in a series of actions designed to punish and seize the profits of individuals who disregard federal and state laws.''

The charges came as lawmakers in the U.S., the company's main market, are seeking to crack down on online gambling, a $12 billion-a-year business. Last week, the House of Representatives approved legislation designed to stifle Web gambling by forbidding credit card companies from collecting payments to Internet casinos.

Betonsports, which gets most of its business from running a sports book and also offers casino games and poker, said earlier today that Carruthers had been detained in the U.S. as he changed planes.

The company's shares fell 17 percent, by 24.5 pence to 122.5 pence, in London. The percentage drop was the biggest since November 2004.

$48.3 Million

U.S. gamblers accounted for almost three-quarters of the $48.3 million in customer deposits paid to Betonsports in the fiscal first quarter ended May 6.

Along with the criminal charges, the U.S. also filed a civil case in St. Louis federal court, asking that Betonsports be ordered to stop taking bets from the U.S. and return money held by U.S. bettors in wagering accounts. U.S. District Judge Catherine Perry issued a temporary restraining order granting the request today and said a hearing would be held within 10 days.

The indictment alleges that Kaplan, 47, started his gambling enterprise in New York in the early 1990s. After being arrested in May 1993 on New York state gambling charges, Kaplan moved the betting operation to Florida, and later, offshore to Costa Rica, according to the court papers.

Kaplan is alleged to have failed to pay federal wagering excise taxes on more than $3.3 billion in bets taken from the U.S. The indictment seeks the forfeiture of $4.5 billion from Kaplan and other co-defendants.

A warrant has been issued for Kaplan's arrest, the Justice Department said. Carruthers, 49, is in custody in Ft. Worth, Texas.

Peter Wilson, media director for Betonsports, and two of Kaplan's siblings were also charged. The three other indicted companies, all based in Florida, are Direct Mail Expertise Inc., DME Global Marketing and Fulfillment Inc. and Mobile Promotions Inc.