The BBC iPlayer is now an undeniable success with consumers. The technological mistakes and management waste of its lengthy gestation are almost forgotten in the flush of popular excitement surrounding the fact that now - at last - quality television is available on demand on the web.

A hostage to this success, the Corporation now faces its next big internet gamble. The price for a bad bet this time could be much higher, threatening the unique way the BBC is funded.

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, ave 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.