A high-level Yahoo female executive struck back with a vengeance Wednesday against a lawsuit alleging she sexually harassed a software engineer, calling the accusations "outrageously false" and "simply inhumane."

In a detailed countersuit, Yahoo mobile app executive Maria Zhang is now suing recently fired engineer Nan Shi for defamation and infliction of emotional distress, saying her claims of sexual harassment are fabrications that have damaged her reputation as well as the search giant's.

Shi filed a lurid lawsuit last week against Zhang, a key mobile app executive at Yahoo, alleging that she was forced to have sex against her will on multiple occasions in exchange for promises of a "bright future at Yahoo." Shi, in the lawsuit, recounted numerous sexual encounters and alleges she was fired after reporting the allegations to Yahoo.

But Zhang argues that Shi, angry over the fact that repeated poor job reviews led to her termination, concocted the story to extort money from Yahoo.

"Shi and Zhang never had sex," the countersuit says. "Shi fabricated that lie with absolutely no regard for the truth or the harm Zhang would suffer as a result of her false allegations."

Yahoo investigated Shi's claims of sexual misconduct and found no evidence, citing the fact there were no emails, texts or other exchanges between the two women that were provided and no accounts from other employees to back up the allegations, according to court papers.

Matthew Fisher, Shi's attorney, could not immediately be reached for comment.

Zhang's startup company, Alike, was acquired by Yahoo last year, and she was working on developing a mobile app for Yahoo that would steer smartphone users to nearby places that were identified as favorites. Shi was one of the employees Zhang brought on board in the acquisition.

Shi claims in her lawsuit that Zhang forced her to work grueling hours, including conducting work "right after sex."

In an interview last week, Shi described being forced to have sex with Zhang, including describing one encounter in her apartment. Born in China, Shi said that she did not initially report the alleged harassment to police or Yahoo because she feared retaliation and the end of her career.

The legal battle will now unfold in Santa Clara County Superior Court.

Howard Mintz covers legal affairs. Contact him at 408-286-0236 or follow him at Twitter.com/hmintz.