South Korea's top airline Korean Air Lines Co. is poised to issue bonds worth up to 300 billion won ($245 million) in April in an effort to secure working funds, industry sources said Thursday.

The amount of Korean Air's planned debt sale, which is currently estimated to range from 200 billion won to 300 billion won, could rise depending on market demand, according to the sources.

The national flag carrier is expected to use the proceeds for refinancing maturing bonds and other operating purposes.

Korean Air, the larger of South Korea's two full-service air carriers, has been raising funds through debt sales since last year.

Last year, the company floated bonds worth 350 billion won in April, 350 billion won worth of environment, social and governance (ESG) bonds in July and 270 billion won worth of bonds in April. In January this year, Korea Air sold bonds worth 300 billion won.

ESG bonds are a type of sustainability debt offering aimed at financing corporate activities in environmentally friendly and sustainable projects. (Yonhap)