The nation's financial industry has cut about 31,000 jobs so far this year via voluntary retirement programs or other measures, data showed Thursday, as the financial sector suffers from slow growth and slim margins.

The decline in financial jobs also came as financial firms shut down their physical branches as customers are increasingly using banking and other financial services on personal computers and smartphones.

According to data by Statistics Korea, the number of employees at financial and insurance firms stood at some 767,000 people as of May, down about 20,000 people from the same month last year.

It marked the biggest monthly decline since October 2015, when the financial sector's jobs were reduced by some 27,000.

The number of employees at financial and insurance firms shrank to some 739,000 people in July 2009, in the aftermath of the 2008 global financial crisis.

In June 2013, the number rose to some 889,000 people. However, it has been on a steady decline since then.

The trend is expected to continue as more customers prefer digital transactions, instead of visiting physical branches.

In January this year, Kookmin Bank cut 2,795 jobs via a voluntary retirement program. KDB Life Insurance also plans to cut 200 jobs via a voluntary retirement program.

Citibank Korea, the South Korean unit of Citigroup, has announced a plan to reduce the number of physical branches to 32 from 133 in the country. (Yonhap)