US law enforcement leaders said on Wednesday that computer attacks were one of the fastest-growing areas of crime and that continually updated technology made it nearly impossible to keep track of the problem.

Addressing a Senate subcommittee on Internet security, Attorney General Janet Reno said last week's attacks on major commercial websites showed how important it was for the United States to devise a co-ordinated strategy against cyber-crime.

"How we deal with cyber-crime is one of the most critical areas we face," said Reno.

Reno called for a five-year plan to deal with the issue and said computer equipment needed to be standardised as continually updated technology meant the costs of resolving the problem were extremely high.

"It is becoming obsolete practically before we get it installed and the costs can be astronomical," she said.

In addition, Reno said tougher penalties should be imposed on cyber-attackers to deter them from causing havoc on the internet.

FBI progress

Reno's testimony to the Senate subcommittee came a day after President Bill Clinton met computer executives at the White House to plot strategy to prevent future attacks such as last week's in which hackers disrupted key websites for several hours, causing millions of dollars in lost revenues.

Commenting on last week's attacks on sites such as Yahoo!, eBay and Amazon.Com, Reno said computer crime investigators were working around the clock to catch the perpetrators.

FBI Director Louis Freeh said he was pleased with progress made in the investigation, which was being conducted as wide afield as Germany and Canada.

He also explained that cyber-crime poses a significant threat to national and economic security in the United States and the FBI's caseload has increased dramatically in recent years.

The FBI said it opened 547 "computer-intrusion cases" in 1998 and the number more than doubled to 1,154 in 1999.

"In short, even though we have markedly improved our capabilities to fight cyber intrusions the problem is growing even faster and we are falling further behind," Freeh said.