OB Beer, South Korea’s leading beer producer, plans to take legal action to combat the spreading of rumors that its Cass brand was mixed with disinfectant solution, company officials said.

OB has requested a cyberinvestigation into who posted the online messages claiming to have witnessed the contamination process, warning customers against consuming Cass beer.

“When beer gets exposed to high temperature and strong sunrays in the summer, it can develop a bitter chemical taste and a unique odor,” said a spokesman from OB Beer said. “This, however, is not harmful to our health in any way, contrary to the rumors online. We’ll do whatever it takes to find who has put up such deceitful posts.”

In June, complaints began to spiral online about the unpleasant smell of disinfectant detected in the canned, bottled and draft beer supplies of Cass. 

The rumor appeared to gain more traction when underground newsletters began to spread on Kakao Talk last week. In the newsletter, a writer claimed that he had “witnessed disinfectant materials being mixed with beer in the manufacturing process” and that “people, especially adult women of childbearing age, should not drink Cass beer produced between June and August.”

Some believe OB’s rivals may have circulated the rumors to win over more customers in peak sales season.

The government, meanwhile, also has become involved.

Up to 18 related complaints ― that they tasted disinfectant in the beer ― have been filed with the Ministry of Food and Drug Safety. Six of the complaints were written off after the ministry tested them and found them not to contain any harmful substances. Another six have yet to be confirmed as safe, while the remaining six complaints were retracted by those who had submitted them.

In response to lingering controversy, Food and Drug Safety Minister Chung Seung said he would visit OB’s manufacturing plant in Gwangju on Wednesday to overlook the manufacturing process.

OB is the nation’s top beer manufacturer with a dominant market share of 60 percent as of March 2013, according to the Korea Alcohol and Liquor Industry Association.

By Suk Gee-hyun (monicasuk@heraldcorp.com)