WASHINGTON – U.S. authorities said Friday a juvenile had been arrested and charged with releasing a variant of the Blaster Internet virus that led to an attack on Microsoft computers.

The youth was the second person charged in the past month in connection with the virus, which hit hundreds of thousands of computers around the world.

Because the youth is under 18, authorities are not permitted to disclose his or her identity or other details about the case, including the location of the arrest.

The U.S. Justice Department said the latest youth arrested helped release the RPCSDBOT version of the worm, which directed infected computers to launch a "denial of service attack," flooding Microsoft's computer network.

The youth was charged as a juvenile with intentionally causing damage and attempting to cause damage to protected computers.

"Computer hackers need to understand that they will be pursued and held accountable for malicious activity, whether they be adults or juveniles," said U.S. Attorney John McKay in Seattle, Washington, who headed the investigation with the FBI and other agencies.

McKay said the investigation was not over and urged anyone with knowledge of the case to come forward.

In late August, Jeffrey Lee Parson, 18, of Minnesota was charged with creating and spreading the so-called B variant of the worm, which quickly infiltrated and clogged computer networks worldwide. Parson, known online by the nickname "teekid," faces up to 10 years in prison and a fine of up to 250,000 dollars on the charge of intentionally causing and attempting to cause damage to a protected computer used in interstate commerce.

The Blaster worm started a denial of service attack against Microsoft by sending millions of requests for automated software updates, flooding the company's computer systems. The virus also carried a message to Bill Gates, the Microsoft founder and chairman, saying: "Billy Gates why do you make this possible? Stop making money and fix your software!!"

The virus spread to hundreds of thousands of computers around the world in mid-August and was among a series of worms that clogged the Internet, causing an estimated five million to 10 million dollars in damage. It forced computer shutdowns at the Federal Reserve Bank of Atlanta, Georgia and the Maryland state motor vehicle offices.

The recent spate of viruses, including the Blaster and SoBig worms, have experts worried about the new breed of virus, which spreads quickly and clogs computer networks, with the potential for hackers to take control of thousands of computers.