South Korean police on Wednesday raided the headquarters of Starbucks Korea as part of an investigation into the company's controversial 'Tank Day' advertising campaign, which allegedly defamed activists killed during the country's historic pro-democracy protests.

According to AFP, the raid was confirmed by Starbucks Korea's local operator, Shinsegae Group.

'The Seoul police raided the headquarters of Starbucks Korea this morning as part of the ongoing investigation,' a Shinsegae Group spokesperson told AFP.

The investigation follows public outrage over the 'Tank Day' campaign, which critics say insulted the memory of pro-democracy activists who lost their lives during one of South Korea's most significant democracy movements. Further details of the investigation are awaited.