Image copyright Getty Images Image caption Playboy founder Hugh Hefner claims he helped to inspire the sexual revolution of the 1960s and 1970s

Playboy Enterprises is exploring a possible of sale of the US adult entertainment group, reports say.

The Playboy empire could fetch more than $500m (£354m), say sources quoted by news outlets including the Wall Street Journal and the Financial Times.

The reported move comes after Playboy magazine stopped publishing nude photos saying they had become outdated.

Circulation numbers have plummeted to about 800,000 last year from 5.6m copies in 1975.

Investment bank Moelis & Co has reportedly been hired to handle the sale process.

Mr Hefner founded Playboy in 1953 with actress Marilyn Monroe as its debut centrefold "Playmate of the Month".

It quickly became a well-known brand and its logo of a bunny wearing a bow tie has been used for a variety of businesses, including clubs and restaurants.

Playboy Mansion

Image copyright Getty Images Image caption The Playboy Mansion in Los Angeles is infamous for its wild celebrity parties

The company's financial details are not easily available after Mr Hefner and investment firm Rizvi Traverse Management took the company private in 2011.

But under that deal, Playboy was valued at around $207m.

According to the reports, Playboy was approached about the sale of the entire company after Mr Hefner's home was put up for sale in January.

The Playboy Mansion - famous for its decadent parties - has a $200m asking price and includes a lifelong lease for the velvet jacket-wearing Mr Hefner.

If sold at that price, the Los Angeles property will become one of the most expensive private residences in the US.

Free porn

Image copyright Getty Images Image caption Playboy announced last year that it would stop publishing images of naked women

The flagship magazine is struggling to attract subscribers and advertisers after dropping its famous nude spreads.

Playboy chief executive Scott Flanders has said the shift in the company's strategy is due to its inability to compete with the availability of free internet pornography.

It has since toned down its content and images to be "PG-13" in order to attract more traffic to its website and social media platforms.

Overall, the publishing industry is expected to lose $4bn in advertising sales over the next four years.