Hackers have gained unrestricted access to the BBC's iPlayer internet television service.

The loophole in the corporation's anti-piracy systems means hackers can download BBC shows without any copyright protection.

The iPlayer system allows internet users to watch BBC shows such as Top Gear and Doctor Who online, or to download them onto a computer.

The BBC agreed with production companies to include anti-piracy measures in all programmes.

The anti-piracy software, called digital rights management (DRM), means new shows disappear after one week and files downloaded onto a computer have a 31-day expiry rate. After that they are no longer viewable.

Hackers, however, have found a back door into the system which allows them to download unprotected versions of any programme.

One hacker told The Guardian: "The BBC accidentally opened the floodgates and gave the world DRM-free downloads.

"If only it were down to something like poor design, decisions and ineptitude."

However, the BBC said that the iPlayer system was still in its trial phase, known as "beta", and that it was working to solve the problem.

A spokeswoman said: "This is not unusual or surprising. We made it clear that the BBC iPlayer on iPhone and iTouch is currently in beta, which enables us to pick up on such issues and find a solution before we roll the service out in full in due course."

"We’ve released a fix to prevent unrestricted downloading of streamed TV programmes on BBC iPlayer. Like other broadcasters, 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."

Recent figures show that BBC programmes were viewed online 17 million times between Christmas and mid-February.

However, some campaigners have protested against the iPlayer restrictions, arguing that Britons who have already bought a TV licence should have unrestricted access to the shows.