South Korean firms' business sentiment rebounded for the first time in four months in September.

According to the Bank of Korea on Tuesday, the business survey index(BSI) for September for all industries stood at 75, up one point from the previous month.

The index had been slipping for four straight months from 81 in May. The nation's consumer sentiment, which was released last week, also rebounded for the first time in four months.

Local manufacturers' business sentiment remained at 73, unchanged from August when the index marked the lowest level in 20 months.

The index for non-manufacturing industries rose two points to 76.

The BSI measuring all industries' expectations for October came to 77, unchanged from the previous month.  

The BSI measures corporate confidence. A reading below 100 means that the majority of firms have a negative outlook for the economy.