By BBC News Online's Kevin Anderson in Washington

Teenage hackers stole thousands of internet accounts and used them to scan the networks of two national laboratories involved in the nuclear weapons programme, authorities in the US state of California have said.

The five hackers, aged 15-17, hacked 26 internet service providers in the US and overseas, said Captain Jan Hoganson, of the Sacramento Valley High-Tech Crimes Task Force in California.

They had a list of 200,000 user accounts from Pacific Bell and were able to successfully steal the passwords for about 95,000 accounts.

They used these accounts to anonymously scan the networks of the Sandia and Oak Ridge National Laboratories.

Scientists at Sandia design all non-nuclear components for the nation's nuclear weapons. Oak Ridge was established in 1943 to produce enriched uranium for the nation's first nuclear weapons.

They did not gain access to the labs' networks, but federal officials described the hackers' activities as "unwelcome visits", Captain Hoganson said.

"It's like they went to a locked business at night and rattled the lock," he added.

The hackers have not been arrested but have been contacted by the authorities.

Hackers attack

This is the latest of several high-profile hacks. On Monday, it was revealed that a hacker had stolen thousands of credit card numbers from online music seller cdUniverse.

The hacker attempted to blackmail the site, asking for $100,000 or else he would release the numbers on the Internet.

Some of the cards were used fraudulently to make purchases of more than $1,000, and some card numbers were posted on a website that was taken down only last weekend.

In a separate incident, a hacker was able to redirect traffic from at least nine sites last weekend to a site called HighSpeedNet.net.

The operator of HighSpeedNet told reporters from the technology site CNET that he himself had been hacked and was also a victim, not the perpetrator.

LawNet

US Attorney-General Janet Reno has called for a national computer network to allow law enforcement across jurisdictions to catch criminals.

"The internet is indeed a splendid tool of wonder, but there is a dark side of hacking, crashing networks and viruses that we absolutely must address," she said.

An FBI survey of Fortune 500 companies found that 62% had reported computer security breaches in the last year.

Ms Reno wants to establish LawNet, an online law enforcement agency that would act independent of jurisdiction, being able to sweep across local, state and international borders to pursue criminals.

On a regional level, the Sacramento Valley High-Tech Crimes Task Force is a model for such an agency.

It was established in 1995 in response to law enforcement complaints from Hewlett-Packard and Apple, which have plants in the area.

Ms Reno has in mind something much grander.

"I envision a network that extends from local detectives to the FBI to investigators abroad," she said.