Fresh from its legal tussles with copyright pirates, the Recording Industry Association of America (RIAA) is now encountering even more hassle from hackers.

The music industry group's website has been offline since last Wednesday, according to internet watcher Netcraft.

Security experts believe the RIAA's site was among the targets of the MyDoom.F virus, created to launch mass distributed denial of service attacks (DDoS) against organisations.

The virus was set to activate between the 17th and 22nd of any month, said Vincent Gullotto, vice president of McAfee's antivirus emergency response team.

The RIAA has said in statements that it is working on getting its site back online.

It is still unclear whether the RIAA outage was due to MyDoom or to another cause.

But McAfee said in a statement that if MyDoom was the cause it indicated that tens of thousands of computers were infected, mostly in Europe.

The current outage now exceeds the RIAA site's four-day period offline in July 2002, which was also attributed to a DDoS attack.