Fans logged on to song-swapping site Napster in droves this weekend in a bid to beat a promised filtering system.

Napster promised US District Judge Marilyn Hall Patel in a hearing on Friday that a filtering system would be fitted to the infamous web service over the weekend.

In a bid to preempt an injunction that would shut down the site, Napster attorney David Boies, told the US court: “We’ve had a group of people at Napster working night and day for two weeks trying to block these names."

Boies promised the filter would be brought online at the weekend. But yesterday afternoon saw record numbers logging in, with more than 11,000 users sharing over 2.2 million files. Napster couldn't make the blocking work.

Napster hit back, expressing the difficulties of installing such a system.

“We will hopefully have something up and running by the end of the week,” said a Napster spokesperson.

Napster is trying to block music tracks record companies have identified on a list of tracks by title, artist and one or more of its file names on the site.

But there are several listings for each tune, and many spelling mistakes, which means Napster may have difficulty screening all the variations for each song.

Friday’s hearing did not progress the case any further but a judicial ruling is expected this week.