A former top female executive at Anheuser-Busch InBev NV has sued the world's largest brewer for gender bias, accusing it of paying women less than men while maintaining a frat party atmosphere.

Francine Katz said she filed the lawsuit on Monday in a Missouri state court in St. Louis, after leaving the company in December following a 20-year career there.

She is seeking lost wages, punitive damages and other remedies from the maker of beers including Budweiser, Bud Light, Bass and Stella Artois.

Anheuser spokeswoman Terri Vogt called the claims unjustified, saying Katz was compensated fairly. She said the company firmly believes in treating all employees fairly and prohibits discrimination on the basis of gender.

According to the lawsuit, Katz was chief communications officer at St. Louis-based predecessor Anheuser-Busch Cos Inc and in 2002 became the first woman appointed to that company's strategy-setting committee.

But in September 2008, when Anheuser was being acquired by Belgium's InBev, Katz said she learned through a draft regulatory filing that she and the other woman then on the 17-person committee were making less than male counterparts.

Katz said that by 2007, her base salary and bonus were only 46 percent of what her predecessor on the committee, John Jacob, had made six years earlier.

In a statement, Katz said that on numerous occasions she complained about pay disparities to executives including former Chairman August Busch III and current President David Peacock.

My requests were ignored or met with hostility and misinformation, she said.

The lawsuit also contends that Anheuser maintained gender bias in pay and promotions, appointed few women to top jobs and committees, excluded women from informal social networks, and maintained a locker room and frat party atmosphere.

Katz and her lawyer were not available for further comment.

The case is Katz v. Anheuser-Busch Inc et al, Missouri Circuit Court, 22nd Judicial District, City of St. Louis, No. 0922-CC09513.