NEW YORK (Reuters) - A New York state appeals court ruled in favor of billionaire investor Leon Black on Thursday, rejecting a defamation claim by a woman who also accused the Apollo Global Management ( APO ) co-founder of rape and sexual abuse.

In a 4-1 decision, the Appellate Division in Manhattan said Guzel Ganieva's October 2015 nondisclosure agreement covered all her claims against Black, including that he defamed her by saying she tried to extort him.

It also said that even if Ganieva signed the agreement under duress, she "ratified" it by accepting $9 million from Black, including a $100,000 monthly stipend, before suing in June 2021.

"We recognize the trauma attendant upon sexual abuse," the majority wrote. "However, we disagree with the dissent that the same principle should allow plaintiff to repudiate a contractual arrangement after accepting its benefits for over five years."

Black denied Ganieva's claims.

The dissenting judge said Ganieva was entitled to sue because the former Russian model remained under "the same continuing duress" until March 2021 when she first spoke out about her six-year relationship with Black, which ended in 2014.

Ganieva's lawyer did not immediately respond to requests for comment. A spokesman for Black had no immediate comment.

The lawsuit stemmed from a March 2021 interview where Black acknowledged having a consensual affair with Ganieva, and said she extorted him based on threats to go public.

He was responding to Twitter posts where Ganieva accused him of years of sexual harassment and abuse.

A trial judge had dismissed Ganieva's claims in May 2023.

Black, 73, is worth $17.1 billion according to Forbes magazine.

He is also defending against a lawsuit in Manhattan by an autistic woman who said he raped her in disgraced late financier Jeffrey Epstein's mansion in 2002, when she was 16.

Lawyers for Black have called the woman's claims "categorically false" and a "malicious smear."

Black stepped down as Apollo's chief executive in 2021 after a review by an outside law firm found he had paid Epstein $158 million for tax and estate planning.

The case is Ganieva v. Black, New York State Supreme Court, Appellate Division, 1st Department, No. 2023-05694.