Activision has said that sales of its recently released Guitar Hero 5 haven't been impacted by MTV Games’ rival music offering The Beatles: Rock Band.

Dan Rosensweig, head of the Guitar Hero division, said that the release of The Beatles: Rock Band “did not affect our sales”.

Activision’s franchise has outsold MTV’s by four to one in the US and by nine to one in other markets, Rosensweig also told the Financial Times.

Nevertheless, MTV parent Viacom has said that sales of The Beatles: Rock Band have exceeded expectations. “It’s been terrific,” Viacom chief executive Philippe Dauman said. “Sales have exceeded our internal projections and we’ve sold 25 per cent of our inventory in the first week.”

On Monday Guitar Hero 5 debuted atop the UK all formats chart, while The Beatles: Rock Band entered at number four. Opening month US sales figures for the games will be revealed by the NPD Group in October.

During the first eight months of 2009, sales of music videogames were down 46 per cent in the US marketplace, according to the NPD Group.

[Correction: We originally reported that Rosensweig had said that Guitar Hero 5 had outsold The Beatles: Rock Band by four to one, when in fact he was referring to overall franchise sales. Thanks, Industry Gamers]