Hackers have found a way around the anti-piracy settings on the iPlayer, the BBC's internet TV service, meaning that millions of viewers were potentially able to download programs from the site and keep them indefinitely.

Using the loophole, viewers were able to circumvent the usual anti-piracy controls on the iPlayer site which mean that once a show has been downloaded, it disappears from the viewer's computer after 30 days.

The BBC said today that it had fixed the problem, and that it didn't know how many programs had been downloaded using the 'hack', but added that viewers would have had to have been "quite technically inclined" in order to use it.

The iPlayer, which allows viewers to watch BBC programs via the web for up to a week after they have been broadcast, has been enormously popular since it was launched last year, and recent figures suggest that more than 17 million shows have been streamed or downloaded since Christmas.

But the service, which has cost several million pounds to introduce, has always boasted a rigorous set of copyright protection measures to reassure TV production companies whose content is made available to viewers on the BBC's site.

One hacker said it took him only 12 minutes to find the loophole and make it work, and that the hack would open up any program available on the iPlayer to be downloaded without copyright controls, which are provided by so-called digital rights management software.

As many as 250 programs are available on the iPlayer at any one time, according to the BBC.

"The BBC accidentally opened the floodgates and gave the world DRM-free downloads," a hacker with knowledge of the breach told the Guardian. "If only it were down to something other than poor design, decisions and ineptitude."

The BBC said today: "We’ve released a fix to prevent unrestricted downloading of streamed TV programmes on BBC iPlayer. The security of rights-protected content online is an issue we take very seriously. It’s an ongoing, constant process and one which we will continue to monitor."

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