A British company is working with Sony to develop next-generation copyright protection technology that allows CDs to be copied a specific number of times before locking them down.

Sony has shipped nearly two million CDs using copy protection from First4Internet, an Oxfordshire-based software house. The software allows the music company to control the removal of files and the making of backup discs.

Mathew Gilliat-Smith, chief executive at First4Internet, told vnunet.com: "I think we were the first to develop this in concept but others are in there now. Sony is taking the lead, although we are in contact with other music labels."

He explained that the software could allow users to make one or more backup copies of music, and would allow users to transfer music from discs onto their hard drive.

This could be achieved without stripping out digital rights management software, and the number of times a CD can be copied is customisable by the music company.

Special care has been taken to make sure that the software is compatible with existing CD players. It is compliant with the Philips and Sony CD standards and with RIAA specifications.

First4Internet started out providing a similar service for record companies to protect master discs from being copied and distributed. It has now translated that technology for the larger market.

To date the copy protected CDs have only been released in the US and for a limited number of artists. Other countries are also reported to be starting trials soon.