Sony Computer Entertainment America have confirmed this weekend that third-party publishers are not compelled to release their games in digital form - in addition to physical UMD releases on PSP.

However, if they don't deliver digital copies via the PlayStation Store, Go users are of course unable to play the new games - a number of games having hit UMD in recent weeks without being available online.

"It's up to individual third parties to decide if and when to publish their UMD releases on PSN. Most, if not all, are on board, as this is a revenue opportunity for them," chief Eric Lempel tells Joystiq.

One publisher - - has already said it has no plans to release digital copies of their games for PSP Go. That said, this is likely to change if the new proves a success.

By Luke Guttridge