The hackers, apparently acting under the name Operation Payback, are believed to have originally planned to attack the site belonging to MOS lawyers Gallant Macmillan.

But the legal firm’s techies were wise to the move and the hack was switched to the British record label, which is getting flak for what many see as an over-vigorous approach to suspected illegal file-sharers.

Solicitors acting for the dance music label have sent letters to thousands of Internet users believed to have illegally downloaded music. They say their client is determined to take them to court and extract substantial damages, unless the suspect immediately pays a sum of about £350 ($556) as compensation.

Gallant Macmillan was due back in London’s High Court Oct. 4 to obtain the names and addresses of a “large number” of broadband users from PlusNet, BSkyB and Be Internet. The hearing had been adjourned from Sept. 21.

However, British Telecom – which owns PlusNet – won a further adjournment until Jan. 11. It said it needs to see details of the security system that would be used to store its customers’ data.

It’s asking for a moratorium on legal applications to obtain details of its customers who allegedly shared files online, as a result of last week’s high-profile data breach at London law firm ACS:Law.

The leak resulted in thousands of customers’ details from various ISPs including PlusNet being published online.

Hackers have also knocked out the websites of the Motion Picture Association of America, the Recording Industry Association of America and also ACS:Law’s website, which led to the subsequent security breach.

Consumer protection organisation Which? recently warned those in receipt of an ACS:Law letter and questionnaire to ignore it. It says it’s had so many complaints it’s asked the Solicitors Regulation Authority to examine the file-sharing correspondence sent by lawyers including ACS:Law and Davenport Lyons.

There have been earlier instances when lawyers acting on behalf of Ministry Of Sound and other labels wanting the details of suspected file-sharers have been given a broad hint that the courts are no longer rubber-stamping these applications.

In the earlier hearing Sept. 21, judge Chief Master Winegarten told Gallant Macmillan lawyers that sending letters to countless thousands of potential pirates was like using “a huge sledgehammer to crack a nut.”

The BPI, the arch-champion of tighter Internet copyright laws, has also questioned the lawyers’ enforcement tactics.

Click here for the Ministry Of Sound website.