Hugh Hefner and his fiancee, Playboy Playmate Crystal Harris, arrive at the opening night gala of the 2011 TCM Classic Film Festival featuring a screening of a restoration of 'An American In Paris' in Hollywood, California April 28, 2011.[Photo/Agencies]

Playboy founder Hugh Hefner said on Tuesday his wedding this weekend has been canceled because his 25-year-old fiance, a Playmate from his magazine, changed her mind.

Hefner, 85, and Crystal Harris were due to tie the knot in front of more than 300 guests at the Playboy Mansion in Los Angeles on Saturday. It would have been Hefner's third marriage.

"The wedding is off. Crystal has had a change of heart," Hefner wrote on Twitter.

News of the split was first reported by TMZ, which said the couple had "a nasty argument" on the phone over the weekend and Harris moved out of the mansion.

Hefner proposed to Harris on Christmas Eve, he announced on Twitter at the time. Since then Hefner has been planning the nuptials in between serving as hands-on editor of Playboy and entertaining family and friends at movie screenings and backgammon games.

A two-hour special featuring wedding highlights was due to air July 13 on the women's cable channel Lifetime.

Hefner was divorced from his second wife, Kimberley Conrad, in 2010 after a lengthy separation. His first marriage to Mildred Williams ended in divorce in 1959. He has two children from each marriage.

Hefner, known around the world by his nickname, Hef, has championed sexual freedom and civil rights, published stories challenging McCarthyism and the Vietnam War, and backed gay causes and the legalization of marijuana.

With a cover featuring a calendar photo of Marilyn Monroe, Hefner put together the first issue of Playboy on the kitchen table in his Chicago apartment in 1953 at a cost of $600. It sold 51,000 copies -- enough to finance a second issue -- and led to a multimillion dollar international corporation, which Hefner recently took private.

Raised in San Diego by British parents, Harris met Hefner at his annual Halloween party in 2008.

She moved in to the mansion after a few weeks and became Playboy's Playmate of the Month in December 2009. She will be on the cover of the magazine's upcoming July issue.