The billionaire founder, chairman and chief executive officer of Wynn Resorts Ltd has denied the allegations as "preposterous" and accused his ex-wife of instigating them for her own gain in litigation against him and his company.

The regulatory inquiry was revealed on Tuesday in a statement that CNBC and several other news outlets attributed to Nevada Gaming Control Board Chair Becky Harris, whose agency oversees enforcement of casino and gambling operations and licensing in the state.

"After completing our review, the Nevada Gaming Control Board is conducting an investigation with regard to the allegations of sexual misconduct involving Steve Wynn. The Nevada Gaming Control Board will conduct its investigation in a thorough and judicious manner," Harris was quoted as saying.

A spokesman for Wynn Resorts, Michael Weaver, said the company "will fully cooperate with any review by regulators."

Reuters was unable to independently obtain a copy of the statement, but one source with knowledge of the situation confirmed that media reports citing the statement were accurate.

Wynn, 76, resigned as finance chairman of the Republican National Committee on Saturday, a day after the Wall Street Journal reported he had routinely subjected women who worked for him to unwanted sexual advances for decades..

His former spouse, Elaine Wynn, whom he accused of fomenting false allegations against him, has denied through her lawyer that she did any such thing.

The company's stock dropped more than 10 percent on Friday after publication of the Journal's article, closing the day at $180.29 per share on the Nasdaq exchange.

Hours later, the Wynn Resorts board said it had formed a special committee to conduct its own inquiry into the accusations. That panel is chaired by Patricia Mulroy, who sits on the board's corporate governance and compliance committees and is a former member of the Nevada Gaming Commission.

The Journal report marked the latest in a wave of sexual abuse and harassment allegations against powerful men in the United State during the past year, especially in the media and entertainment industries and politics.

The Journal said its report was based on interviews with dozens of people who had worked for Wynn and that none of the 150 individuals contacted for its story had reached out to the newspaper.

(Reporting by Steve Gorman in Los Angeles; Editing by Paul Tait and Neil Fullick)