Global credit appraiser Moody's Investors Service has maintained South Korea's credit rating at "Aa2" with a stable outlook.

In a statement on Wednesday, Moody's said the decision reflects the very strong fundamentals that have underpinned South Korea's resilient recovery from the COVID-19 pandemic shock.

Since upgrading South Korea's rating from "Aa3" in December 2015, the agency has kept the grade at its third-highest level. Seoul's sovereign credit rating also marks the second-highest among countries in Asia, following Singapore.

Moody's revised up its growth outlook for South Korea this year from three-point-one to three-point-five percent, citing a strong demand for exports and an accommodative fiscal strategy.

It, however, warned Korea's fiscal discipline could be tested amid historically high debt levels. 

South Korea's national debt grew by a record figure last year, driving the government's expansionary fiscal policy. Its debt-to-GDP ratio jumped to 44 percent in 2020 and is on its way towards 60 percent, according to the Moody's report. 

The ratings agency also noted rapid aging and North Korea-related risks as primary credit challenges for the country.