HONG KONG - A Hong Kong court's order outlawing "ladies nights" on gounds of discrimination has drawn the ire of club and bar owners, who said the ban has slashed their business by as much as half and vowed to resume the practice.

The District Court ruled in April that the promotion of ladies' nights - which usually offers cheaper admission and drinks to women only - was discriminatory against men.

The case was filed last year by the city's Equal Opportunities Commission on behalf of a man who accused a disco club of breaching sex discrimination laws with its ladies' night promotion.

The court also ordered the company to compensate the man.

The case sent a chill through night spots in the territory, with many cancelling their ladies' nights, South China Morning Post reported on Monday. Business at some establishments have suffered as a result.

"Gentlemen used to spend between HK$500 (S$87) to HK$600 in one night, but now the amount has fallen to around HK$400," Mr Max Wong, manager at J1 Club in Tsim Sha Tsui, was quoted by the Post as saying.

Some bars in the Central business and shopping district have seen business plunge by half, the report said, citing Mr Wing Chin, vice president at the Hong Kong Bar and Club Association.

"We must do something before a tide of closure emerges," said Mr Chin, noting that business at clubs and bars was down 20 to 30 per cent in the first half of year, compared to a year ago, due to belt-tightening amid uncertain economic outlook.

"We will not cut the ladies' nights just because of some unreasonable ruling," said Mr Chin, adding it was a "basic practice" in the industry for decades.

He called on bar operators to resume the practice, shrugging off the risk of legal challenges.

"We will deal with the case if the practice incurred further legal actions," he said.

The association has even highlighted clubs which continue to host ladies' nights in its new app, BarMap. It has seven bars currently listed.