Ju Biung-ghi, chairman of the Fair Trade Commission, speaks during a press conference held at Sejong, Tuesday. Yonhap

Korea's antitrust watchdog has no grounds to investigate Starbucks Korea over the coffee chain's controversial marketing campaign allegedly mocking the 1980s democracy movement, though it would be a "serious" issue if done intentionally, its chief said.

Ju Biung-ghi, chairman of the Fair Trade Commission (FTC), made the remark during a press conference held in the central city of Sejong on Tuesday in response to questions about the watchdog's potential action against the Korean unit of the global coffee chain.

"(Starbucks Korea) claims to have used the word 'tank' in a neutral way, but if it is revealed that the company had other intentions, it should apologize to the public and customers," Ju said.

"If the phrase used in the marketing campaign was intended to deceive customers, that would be a serious issue," he added.