Pioneer has developed an optical disc that can hold up to 400GB of data surpassing previously announced prototypes.

The new disc manages to pack 16 layers, each with a 25GB capacity, into a conventional 12-centimetre diameter optical disc. The new discs are similar to Blu-ray Disc technology and slight changes to the hardware on a Blu-ray drive would allow the new Pioneer discs to be used on one.

Pioneer doesn't have any plans to commercially produce the disc but is looking to work with disc manufacturers who would make it themselves. The technology is about ready to enter commercialisation, said Michiko Kadoi, a spokeswoman for Pioneer in Tokyo.

A one-sided Blu-rayDisc has 25GB of capacity, far less than the Pioneer disc.

Currently dual-layer 50GB discs are the highest capacity discs available commercially. Various companies have worked on higher capacity discs and TDK previously announced development of a 6-layer disc with 150GB capacity but that has yet to reach the market.

Getting a clear signal from each recording layer has been a stumbling block for higher capacity discs with more layers, but Pioneer says it has managed to solve this problem by employing technology it developed for DVDs. The new disc has a structure that reduces interference from adjacent layers and so accurate playback is possible from all 16 layers, the company said.

The initial prototype is a read-only disc but the same technology is also applicable to recordable discs.

A current 50GB Blu-ray Disc can store about 6 hours of digital high-definition TV so the higher capacity discs, if commercialised, would be able to expand this to 48 hours.