Electronics giant Panasonic has promised to introduce write-once Blu-ray discs with 4x writing speed.

The firm said that the new discs will be available in 25GB and 50GB versions in July and September respectively.

The new discs have a maximum data transfer speed of 144Mbps, allowing them to copy a 1GB folder in just one minute, while a DVD-RW at 2x data transfer speed will copy the same folder in six minutes.

The speeds are achieved by the application of new phase-change recording technology, according to the company.

Panasonic has applied the technology to single-layer and dual-layer discs for the first time, allowing users to write 50GB data at 4x high-speed without turning over the disc.

"The newly developed recording layer also has a wide power margin at any writing speed from 1x to 4x. This enables high quality recording even if the drive's laser power fluctuates, resulting in greater overall drive compatibility," Panasonic stated.

"The new discs offer extremely low error rates thanks to a new film forming technology which minimises dust generated in the sputtering process.

"The error rate is reduced to one-tenth that of a conventional disc, ensuring high reliability and a high quality recording."