Ashlee Simpson has tuned down a $US4 million offer to pose nude for Playboy.

The sexy singer, the sister of 'Dukes of Hazzard' star Jessica, was approached by the world famous men's magazine to strip off in their pages.

Although she is said to have seriously considered the offer from the publication - owned and founded by legendary lothario Hugh Hefner - Ashlee has decided to keep her clothes on.

Her publicist, Rob Shuter, has confirmed the pop beauty did receive the mega offer but snubbed the opportunity.

However, sources close to Ashlee claim she should pose naked for Playboy to raise her profile.

One told America's In Touch Weekly magazine: "This may be the perfect time for her to do it. It could be one way for her to separate her image from Jessica's."