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.

The iPlayer has been hugely popular with internet users and has been one of the major highlights of the Beeb this year; but ISPs have been quick to respond to this popularity and pointed out that they were losing money.

Some ISPs have also tried to manage BBC iPlayer data, something that the corporation has vehemently opposed and has threatened to blacklist those ISPs which would try to throttle iPlayer downloads.

On his BBC Internet Blog, Ashley Highfield, BBC's director of future media and technology, wrote a post entitled "Hidden Costs" of Watching TV Online? which refered to a previous article written by The Daily Telegraph and in which he attacked the stance and double standards of Internet Service Providers.

The BBC has issued a fix to stop people downloading programmes from the iPlayer website that were intended for streaming on an iPhone or iPod only.

Hackers had discovered an exploit that allowed them to save the programmes to hard disk and share them with others.

Rights issues mean the BBC is only able to offer streamed programmes for up to seven days after broadcast.

A download service for PC users lets viewers keep the programmes for up to 30 days on their PC.

The Digital Rights Management on downloadable programmes from iPlayer was exploited and breached some time ago.

The BBC admitted that it was most likely facing a cat and mouse game with hackers intent on circumventing copy protection.