PlayStation Plus subscribers in Japan will be granted free access to some 250 PSP games for the PS Vita handheld, Sony has announced.

The offer, which runs from September 17 until the end of the year, gives PS Plus subscribers unlimited access to an extensive library of digital PSP games such as Gran Turismo and LocoRoco.

Currently, the PS Vita can access an entire library of PSP games within the PS Store, each of which can be downloaded at a cost. The new PS Plus offer means that many of these games can be downloaded for free, and kept for as long as the PS Plus subscription lasts.

Sony announced the new offer during its pre-TGS press conference on Monday, where it also revealed that developer Atlus is developing Persona 5 for PS4.

It is unclear whether the free PSP games offer will be extended to the US or Europe. Gamespot has contacted Sony for clarification.

Also unclear is which games will be offered for free. The Japanese PSP catalogue on the PS Store consists of more than 370 games, meaning that about two thirds will be available.