A British man was arrested at the end of July on charges that he created and released the W32-Leave.worm, Scotland Yard confirmed today.

In a joint investigation with the FBI, Scotland Yard arrested the 24-year-old man on 23 July under the UK's Computer Misuse Act 1990, confirmed a Met Police spokeswoman.

"We cannot comment too much as he has only been arrested at this stage after a search warrant was issued. He was released and is to return to a London police station in September, either for further questioning or to be charged," the spokeswoman said. The investigation is ongoing, she said.

Under UK law the man's name was not made public, though the Met Police spokeswoman confirmed that he is to be charged with creating the W32-Leave.worm.

The W32-Leave.worm, which was reported by the FBI's NIPC (National Infrastructure Protection Center) in June, when it issued a warning, reportedly helps a hacker to break into a victim's computer. The hacker could then steal or delete files, or use the computer to commit other hacks or launch denial of service attacks.

According to the NIPC's warning, the worm only affects computers that have been infected previously with another virus called the SubSeven Trojan. The worm and trojan work together to complete control of and use the target machine, the NIPC said.

The worm was deemed low risk by antivirus software companies such as Trend Micro. "We don't know of too many cases of the worm infecting systems," said Trend Micro spokeswoman Penny Brennan. Trend Micro did not regard the worm as destructive because it does not do damage to infected systems, instead creating a backdoor for hackers to gain access to infected systems.