An update to the PlayStation Portable (PSP) allows gamers to play PSOne titles purchased at Sony's online store.

Firmware update 3.80 allows the PSP to stream games from PSOne discs played on a PlayStation 3 using the Remote Play function.

Both machines need to have access to a Wi-Fi network for the process to work.

Players will have to reassign some of the buttons on the handheld games console, as it does not have as many as the Sony PSOne controller.

The PlayStation 3 also received its latest firmware update, taking it up to version 2.10. PS3 owners can now play DiVx and WMV files, as well as Blu-ray 1.1 discs.

An added Voice Changer feature also lets players modulate the tone of their voice using five preset levels.

Sales of Sony's PSP more than doubled last week in Japan, according to data from market analyst Media Create.

The PSP sold 184,610 units in the week ending 16 December, easily beating the 91,481 units the previous week.

However, it still trailed behind Nintendo's DS, which saw weekly sales of 222,144 units in Japan.