Store employees of the Korean unit of Starbucks Corporation began a protest over their demanding duties, calling for an improvement in the working environment.

From 10:00 a.m. Thursday, two trucks traveled throughout Seoul with signs expressing their complaints. One traveled through Gangnam district and while a second visited Mapo, Sangam, Hongdae and Shinchon north of the Han River.

The workers have complained about the increased workload stemming from the company's various marketing events, such as a series of promotional events that offers limited edition merchandise for each beverage sold, which often attracts endless queues of customers and collectors.

The rallies are scheduled to be held through Friday.

Starbucks Coffee Korea CEO Song Ho-seop issued an apology to the employees for forcing the exhaustive assignments on them due to a lack of preparation in marketing, and pledged to address their grievances.