Speaking to MTV Multiplayer, Sony Computer Entertainment America's head of PSP hardware marketing John Koller has said the Grand Theft Auto titles have been top sellers on PSP, adding that "no one should sleep" on the GTA franchise.

"That's a tremendous franchise for PlayStation in general," said Koller. "We've had two that are the top two sellers on PSP right now. So, there's definitely continued conversations with Rockstar on all their brands. That's nothing that's left the PlayStation family."

Koller also noted that Rockstar's decision to take the GTA franchise to the DS and release exclusive GTA 4 DLC on Xbox 360 were business decisions.

"To be honest, Rockstar has to manage their business as they see fit. We're very good partners with them. They just launched 'The Lost and the Damned' for 360, so, they need to make their own business decisions. But we certainly have a tremendous relationship with them and always have."

Koller also labelled Chinatown Wars as an "interesting launch" and added "it'll be interesting to see how that sells".

Grand Theft Auto: Chinatown Wars is scheduled for release in the UK on March 20.