Sensation: Demi Moore appared naked and pregnant on the cover of Vanity Fair

According to reports, the divorce papers cited irreconcilable differences.

The couple were married in November 1987, three months after they first met.

The wedding was reported to have cost $875,000 and was a celebrity affair - Little Richard sang at the ceremony.

The couple divided their time between their Idaho ranch, worth $6m, an apartment in New York and a home in Malibu, California.

Their three children, Rumer Glenn, 11, Scout Laurie, nine, and Tallulah Belle, six, still attend school in Hailey, Idaho.

For years Willis and Moore were Hollywood's most glamorous couple.

Powerful showbiz figure

Moore appeared naked on the front cover of Vanity Fair when heavily pregnant and both stars enjoyed successful movie careers.

Since their split Willis has maintained his position as one of the most important world film stars and this week was ranked ninth in a list of the most powerful showbiz figures.

A second list of ranking by celebrity put Willis at number five.

In the early 1990s Moore was one of Hollywood's biggest stars, starring in Ghost and Indecent Proposal, but her career has suffered in recent years. She has appeared in film flops Striptease and GI Jane.

The couple both have humble backgrounds - Willis was raised in New Jersey while Moore was born in Roswell, New Mexico.

The couple retain business interests in the Planet Hollywood chain of restaurants and a new website venture along the same theme.

When the couple split, a former friend of Moore, actress Ally Sheedy - the two women starred in St Elmo's Fire - told US magazine that the marriage had been one of convenience.

"The quickest route to power for an actress in Hollywood is to hook yourself up with someone who can put you in a good position and make yourself into a sex object," she said.