Starbucks (SBUX) headquarters of its South Korean unit in Seoul was raided by police as authorities investigate the company's controversial "Tank Day" marketing campaign, Bloomberg News reported Wednesday, citing Shinsegae Group.

According to Bloomberg, the search is linked to a defamation complaint filed by a civic group against Shinsegae Group Chairman Chung Yong-jin over the campaign, which sparked public backlash and boycott calls after critics alleged it disrespected victims of South Korea's 1980 Gwangju pro-democracy movement.

Bloomberg reported that the campaign triggered a corporate public relations crisis for Starbucks Korea, prompting the company to apologize and withdraw the promotion.

Starbucks and the Shinsegae Group did not immediately respond to MT Newswires' requests for comment.

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