The U.S. Senate's passage of legislation restricting online gambling has sent shares of global betting companies tumbling overseas.

U.S. lawmakers Saturday passed the Unlawful Internet Gambling Enforcement Act, which makes it illegal for financial institutions and credit card companies to process payments for Internet bets.

Shares for global Internet gambling companies plummeted during trading Monday on the London Stock Exchange, shedding nearly seven billion dollars of their market value.

Two leading online British gaming companies, PartyGaming and 888 Holdings,  say they will suspend business operations in the United States. Company officials say the new law makes it practically impossible for U.S. residents to gamble using their Web sites.

The United States is the international gambling market's biggest source of revenue.

President Bush is expected to sign the bill into law in the coming weeks.

Some information for this report was provided by Reuters and Bloomberg.