An outfit claiming to be Anonymous says it is moving to replace defunct fire-sharing website Megaupload, following the latter's demise at the hands of the FBI.

However, a post on an Anonymous Twitter feed warns that the Anonyupload website may be a scam and says the hacking group has "no affiliation" with it.

Megaupload.com was shut down by the FBI in the early hours of Friday after charges were laid against seven individuals, three of which were arrested in New Zealand, including Megaupload's millionaire founder Kim Dotcom.

Anonyupload has called for supporters to join in hosting services in a decentralised fashion to "ensure the safety" of users and "rapid transfer" of files. The new site was registered on Monday and says it will be "launched" on January 25.

The site appears to be advocating a return to peer-to-peer (P2P) file sharing, given Megaupload's centralised service was arguably simpler for law enforcement to take down. P2P users allow others to share files hosted on their own computers.

It also says the group's infrastructure has been set up outside US jurisdiction in Russia, and thanks Mr Dotcom for his "service" adding "try not to make that amount of money next time and it should be alright".

It appears to shun profit-making by stating that the site has a "good economic plan" based on donations: "let's try to not get into a huge system that only works with money". It appears to accept donations via PayPal.

Some commentators say the closure of Megaupload has implications for other cloud hosting or "cyberlocker" services such as Dropbox, RapidShare and Hostfile. The sites have no control over the files users upload, and users have no guarantee the service will not be targetted in a piracy crackdown.

In retaliation for the closure of Megaupload, Anonymous crippled several official websites including the FBI, the US Department of Justice, Universal Music, the Motion Picture Association of America, and the Recording Industry Association of America with distributed denial-of-service attacks on Friday.

Denial-of-service attacks cause websites to temporarily crumble under the weight of millions of requests for page views, disrupting service.

The FBI site is back online, but justice.gov was not at time of publishing.

Anonymous is against the anti-piracy lobby led by music, movie and book publishers. It found allies in opposition to US proposed copyright protection bills which many, including Google, Wikipedia and the father of the web, Sir Tim Berners-Lee, say go too far in censoring the internet. Several US senators withdrew support for the bills late last week.

Voting on the Stop Online Piracy Act (SOPA) and its Senate cousin Protect Intellectual Property Act (PIPA) has been postponed, amid the outcry.

- Sydney Morning Herald