May 29 (Reuters) - A former executive assistant at One Equity Partners sued the private equity firm on Wednesday, claiming she was subjected to sexist and racist conduct and was fired for complaining about it.

Dianna Toomey, an Arab American of Lebanese descent, said in a complaint filed in Manhattan federal court that One Equity (OEP) executives frequently belittled women and a co-worker called her a "dirty terrorist" and other epithets.

The lawsuit claims One Equity's founder and chairman, Dick Cashin, routinely made misogynistic comments and subjected Toomey to unwanted touching. It also alleges that Greg Belinfanti, the firm's president, said he would not meet alone with women because it was "just an invitation to a lawsuit."

Toomey said One Equity has no human resources department so she complained about the conduct "on numerous occasions to anyone who would listen," but no action was ever taken. She was fired in April, weeks after sending a letter outlining the alleged harassment to the company's chief operating officer, she said.

One Equity said in a statement that the claims lack merit and are "comprised of complete fabrications."

"OEP has a strong commitment to diversity, equity and inclusion. This employee was let go by OEP based solely on legitimate reasons, and the firm welcomes the opportunity to defend our reputation," the company said.

Cashin and Belinfanti did not immediately respond to requests for comment.

"Whether a firm has $1 under management or $10 billion, like One Equity Partners, it is required to adhere to the anti-discrimination, anti-harassment and anti-retaliation laws," Michael Willemin, a lawyer for Toomey, said in a statement.

"OEP failed miserably in this regard, and we look forward to holding it and its executives accountable for their conduct."

Toomey was hired as an executive assistant on One Equity's investor relations teams in 2022 and received positive reviews, raises and large bonuses throughout her time with the firm, court documents show.

The lawsuit accuses One Equity of race and sex discrimination and retaliation in violation of federal and New York state and city laws.

Toomey is seeking unspecified damages for pain and suffering, lost earnings and harm to her reputation, and punitive damages. (Reporting by Daniel Wiessner in Albany, New York; Editing by Alexia Garamfalvi, Richard Chang and Rod Nickel)