Kookmin Bank, one of South Korea's biggest retail banks, said Friday it plans to cut about 13 percent of its workforce in a voluntary retirement program next month as part of its efforts to improve productivity.

The bank has offered to pay the equivalent of up to three years' salary to those who are eligible for the retirement program.

So far, about 2,800 employees -- who have worked for the company for more than 10 years -- applied for the program.

The retirement program is set to take effect Jan. 19.

In 2010, more than 3,240 employees left the bank. Last year, the banks slashed 1,100 jobs.

Currently, Kookmin Bank has about 20,500 employees.

Major banks in South Korea have made a series of job cuts in recent years to reduce costs and buttress their bottom lines.  (Yonhap)