Seoul, Oct 7 (IANS): Employees of Starbucks coffee stores staged a demonstration on Thursday to protest against excessive workload stemming from the company's marketing events.

Two trucks hired by Starbucks Coffee Korea workers drove around Seoul from 10 a.m. with signs calling for improved work conditions attached on their sides, reports Yonhap News Agency.

The protest will continue through Friday.

The first-ever protest by the Korean unit of the global coffee chain was triggered by a 50th anniversary event on September 28, which drew huge numbers of customers by offering limited-edition reusable plastic cups.

"Starbucks Korea should resolve manpower shortages by reducing excessive promotional costs and increasing personnel expenditure," read a sign on one of the vehicles.

Another phrase condemned frequent marketing events that leave employees struggling to serve huge numbers of orders.

"The reusable cup event with 650 orders waiting to be served made partners (baristas) shed tears and customers turn their backs," it read.

Song Ho-seop, the CEO of Starbucks Coffee Korea, has recently apologized to employees.

"(The company) apologizes for causing excessive workloads and heavy burden due to its negligence in the preparation process," Song said in an email to employees.

"We will listen to partners' opinions and examine processes to reflect them."