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Elaine Wynn, former wife of Wynn Resorts Ltd founder Steve Wynn, sued him on Monday to get control over her nearly 10 percent stake, worth close to $900 million, in the casino company.

Escalating a battle that followed a bitter divorce, Elaine Wynn said Steve Wynn breached a 2010 stockholder agreement by engineering her ouster from the company's board last April after she faulted its internal controls, his alleged withholding of information from the board, and the "tone at the top."

Casino magnate Steve Wynn and ex-wife Elaine Wynn. REUTERS/Files

In papers filed with a state court in Clark County, Nevada, Elaine Wynn is seeking to void the agreement so she can take control of her Wynn Resorts stake, plan her estate to benefit her daughters, and stop Steve Wynn from misusing the agreement to exert "full and perpetual control" over her life and legacy.

Elaine Wynn controls 9.4 percent of Wynn Resorts' stock, while Steve Wynn controls 11.8 percent, Reuters data show.

Steve Wynn, through a spokesman, called Elaine Wynn "a disappointed ex-wife who is seeking to tarnish the reputation of Wynn Resorts and Steve Wynn and their daughters," and said her lawsuit was "filled with lies and distortions."

In a separate statement, Wynn Resorts accused Elaine Wynn of making "falsehoods and distortions," and said her allegations that the company misused assets were without merit.

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Wynn Resorts controls properties including the Wynn Las Vegas resort, Encore at Wynn Las Vegas and Wynn Macau.

Steve Wynn, 74, also helped develop other Las Vegas hotels including the Bellagio, the Mirage and Treasure Island.

He is worth $2.7 billion, while Elaine Wynn, 73, is worth $1.5 billion, according to Forbes magazine.

The Wynns married in 1963, divorced in 1986, remarried in 1991, and divorced again in 2010, court papers show.

Elaine Wynn's lawsuit also names as defendants Wynn Resorts and General Counsel Kimmarie Sinatra.

It seeks compensatory and punitive damages, including for Steve Wynn's alleged failure to support Elaine Wynn's reelection to the board.

The lawsuit was filed as a counterclaim to a 2012 lawsuit by Wynn Resorts against defendants including Kazuo Okada, a Japanese billionaire.

Okada owned 20 percent of Wynn Resorts before the company forcibly redeemed his stake in 2012. He and Wynn Resorts have traded allegations of illegal conduct in later U.S. litigation.

Wynn Resorts shares closed down 64 cents at $92.83 in Monday trading on the Nasdaq.