US President George Bush signed into law provisions aimed at keeping nuclear, chemical or germ weapons from being smuggled into the country's ports.

The law signed Friday also outlaws Internet gambling, a provision tacked onto the bill that has prompted at least one company - Sportingbet Plc - to sell its US operations for a nominal cost of $1.

It was not clear how the law would affect a long-running dispute between the United States and the World Trade Organization over US ban on online gambling.

US gamblers make up about one-third of the world's online betters, wagering $637 billion in 2003 alone.

Bush, who did not mention the gambling provision, said the SAFE Port Act authorises the development of "21st century inspection equipment" to help check inside cargo containers for dangerous materials.

The bill also requires radiation-detection technology at the country's 22 busiest ports. Only 6 percent of cargo entering US ports is subjected to the scrutiny now put to airborne passengers and luggage.

About 95 percent of America's international cargo traffic is water-borne.

The gambling provision, which has fought an uphill battle in Congress, was tacked onto the popular ports security bill to guarantee its passage.

The law prevents US credit card companies and banks from seeking payment for bets made at online gambling sites.

Online gambling has grown exponentially since the first online casino was launched in 1995. Worldwide Internet gambling revenue in 2003 was estimated at $5.7 billion on about 1,800 websites, and was projected to triple by 2009, according to the American Gaming Association.