Matsushita (which operates under the Panasonic brand name) has announced the first 4X Blu-ray write-once discs, also known as 4X BD-Rs.

The discs will ship in both 25- and 50-Gbyte capacities this July and September, respectively, Matsushita said. The larger 50-Gbyte disc uses two layers. Prices were not announced.

The discs are rated at 144 Mbits/s in both read and write speed, which means they can copy a 1 Gbyte folder in just one minute, Panasonic said.