WWW- LIZA Minnelli’s estranged hubby sexually harassed his male assistant, making crude comments about his manhood and grabbing his rear end, a federal lawsuit claims.

Charles Beyer said he went to work for David Gest [pictured] at his Tennessee home on July 25, 2005, and the oddball producer made “sexual gestures from the beginning, forcing me to use his computer in the master bathroom, making comments such as, ‘You have a small [sex organ], I bet,’ [and] grabbing my butt.”

Beyer claims Gest also “wrote in my calendar on numerous occasions,” leaving directions such as, “Shake my penis, make sure it feels good,” wash it “in hot water” and “dip it in chocolate fudge.”

“All the allegations are false,” Gest’s lawyer, Eddie Bearman, told The Post’s Dareh Gregorian. He called Beyer’s $300,000 suit “a bogus attempt to get money from a celebrity” and noted the Equal Employment Opportunity Commission dimissed Beyer’s complaint against Gest.

Beyer didn’t return our call, but his suit is filled with explicit claims about Gest’s “unwelcome physical and verbal sexual harassment.” Once, Gest allegedly told an employee at a casino that Beyer had “had a sex change” and “was actually a woman.” The employee “came to me while I was with my fiancée and congratulated me on such a good job,” Beyer’s filing says. “It was humiliating.”

Gest supposedly told actress Jane Russell that Beyer was married to his male hairdresser, and once grabbed Beyer’s “private area” – and once paid his bodyguard to grab it, the filing says. After Beyer complained to the EEOC, Gest toned down his physical antics but continued to “make comments about my manhood,” Beyer said.

According to Bearman, Russell denies Beyer’s account, saying it was “made up,” and has offered to testify on Gest’s behalf.

Beyer, 35, claims Gest yelled at him when he stuck up for Minnelli, whom Gest is suing for allegedly beating him up.

“He was taking items such as LPs that were marked ‘Liza’ and began pouring paint on them,” Beyer says. “I told him just send her stuff back . . . I told him she would understand and it would look better for him. He said, ‘HELL NO!!!”

Bearman said Gest has “ample evidence to refute” Beyer’s claims, including numerous witnesses. He also said Gest has been an ideal citizen since moving to Tennessee: “This is a man who’s very helpful to the Memphis community, doing wonderful things – feeding the homeless and other civic-minded deeds.”