Software experts say a privacy glitch in RealNetworks' RealPlayer program means it could secretly collect information about its millions of users.

Earlier this week, RealNetworks apologised after it was revealed that its RealJukebox software suffered from a similar problem.

It subsequently released issued a patch to remove a unique identification number from the software which tracks users' listening habits.

'Harder to fix'

The US security expert who discovered the original flaw, Richard Smith, says the glitch is in RealPlayer could present a serious problem for the software company.

"It's harder to fix because the player has been around for years," Mr Smith, former president of Phar Lap Software, was quoted as saying.

RealNetworks controls around 85% of the streaming media market, with 69 million registered users of RealPlayer.

RealNetworks has yet to comment on the reports.But industry insiders say it is planning to release a new version of the software without the unique identification number.

Identifying users

The identifier is known as a globally unique identifier, or GUID. It transmits information to the company's headquarters details about what music each customer listens to and how many songs are copied.

In the case of RealNetworks, the information sent includes a serial number that could be used to identify an individual.

One of RealPlayer's main rivals, Microsoft's Windows Media Player, also transmits an identifier.

But the ID number cannot be linked to personal information as Microsoft does not require user registration.

The nonprofit group that monitors and enforces the corporate privacy policies of its members, TRUSTe, is planning to investigate whether RealNetworks had broken its privacy promises and whether its previous statement, which TRUSTe had vetted, was adequate.