Rumours of a PSP2 refuse to die, and now new publishing sources have said that Sony has plans to both refresh the PSP with a PSP-4000 model in late 2009, and follow it with a true PSP successor later on.

The sources were unable to reveal much more about either, but it is thought the PSP-4000 will follow in the PSP-3000's footsteps in taking an iterative approach, and that developers are already working on PSP2 games.

As the rumours have swirled about a PSP successor, Sony has neither confirmed, nor ruled it out.

SCEE president David Reeves has said: "There are currently no plans for a PSP2. I go to Tokyo quite a lot and no one has referred to it - I think they have their hands full at the moment".

With regards to this new information, Sony UK has said it would not comment on "rumour and speculation", similar to the stance it took when a company revealed it had been licensed to produce a processor for the PSP2.

We'll be sure to keep you updated with any news we get.