Microsoft' s vice president of entertainment Bryan Lee - the man who oversaw the release of the Zune digital music player - is to retire in the next few weeks.

Lee, who has been with Microsoft for six years, was in charge of business development and marketing of the Microsoft Zune . He will be replaced by J Allard who will take over the same tasks. Allard was previously in charge of the Zune's design and development.

Lee formerly worked on developing the Microsoft Xbox gaming console, the Windows XP Media Center operating system, and Microsoft's IPTV services.

The Microsoft Zune player has been on sale in the US since November, but has struggled to make a mark in the competitive digital music player market, especially against its arch rival, the 30GB Apple iPod .

Microsoft said that Lee's departure was a personal decision which was not related to the performance of the Zune player. The company insisted that it is still on track to sell one million Zunes by the end of June .