WASHINGTON — Internet gambling was quietly strangled in the United States Friday, with new restrictions riding on a port-security bill signed into law by President Bush.

Instead of banning gambling outright, the provision blocks most methods of placing or paying off online bets.

The new restriction will affect as many as 23 million U.S. residents who bet $6 billion on the Internet last year, The Washington Post said.

The Unlawful Internet Gambling Enforcement Act bans gamblers from using any form of payment such as checks, credit cards or electronic transfers to place or settle up online bets.

The law makes U.S. financial institutions responsible for enforcing the ban, the Post said.

The newspaper said the ban is potentially crippling to the worldwide Internet gambling industry, with the United States its largest customer.