Toshiba is close to commercializing new data storage technology that could significantly increase the capacity of the hard-disk drives currently used inside iPods, it said Tuesday.

The company will make the new drives - which could boost iPod capacity to 80GB or more - available in the middle of 2005. Toshiba is developing two 1.8-inch hard-disk drives that use the technology, called perpendicular recording.

Like current drives, the new method relies on storing data in magnetically charged bits. However, unlike current longitudinal recording in which the bits lie flat on the disk surface, in perpendicular they stand upright and thus take up less space. This means there is room for more of them on the disk and so the storage capacity is higher.

The first two drives planned by Toshiba to use the technology will have a recording density of 133Gbits per square inch, which is 37 per cent greater than current drives, said Junko Furuta, a spokeswoman for Toshiba in Tokyo.

The greater recording density could help Toshiba's customers, including Apple, produce thinner and lighter products. For example, one of the drives in development will be capable of storing 40GB of data on a single disk platter. The current 40GB 1.8-inch drive requires two platters to achieve this capacity.

The drop from a dual to a single platter means the overall drive falls in thickness from 8 millimetres to 5 millimetres. Toshiba's second drive will pack two platters and offer a total storage capacity of 80GB, the highest yet for a device of its size.

Other major specifications of the drives, including the weight, average seek time and rotational speed, remain similar to Toshiba's current 1.8-inch drives.

Toshiba won't provide an estimate of the likely price of the drives. It said sample drives are available now. In future it wants to use the technology in its 0.85-inch drive. Employing perpendicular recording along with other new technologies will raise the capacity of the drives from between 2GB and 4GB to between 6GB and 8GB, said Furuta.