Former Gov. Eliot Spitzer of New York has filed a lawsuit against a Russian woman who accused him of an assault at the Plaza Hotel in Manhattan this year, alleging that he is the subject of an extended and expanding attempt at extortion.

The lawsuit, filed in State Supreme Court in Manhattan on Friday, offers new details about the combative and disastrous relationship between Mr. Spitzer — who resigned in disgrace in 2008 after being linked to a high-end prostitution ring — and Svetlana Andreevna Zakharova, 26, who is also known as Lana Travis.

In February, the police investigated a claim and a 911 call made by Ms. Zakharova that Mr. Spitzer had choked her during a meeting at the Plaza Hotel, but she later recanted before returning to Russia and apologized to Mr. Spitzer via email. No charges were ever filed.

In the lawsuit, Mr. Spitzer’s lawyers acknowledged that he had previously agreed to make “certain payments” to Ms. Zakharova to persuade her to not follow through on threats “to reveal publicly and to Mr. Spitzer’s family the existence and purported details of their interactions that she thought would embarrass Mr. Spitzer and his children.”