The global rating agency Moody's Investors Service has cited South Korea among countries that have the fastest aging populations and warned that an aging population can pressure the nation's credit profile.

In an aging-related economic forecast report on Thursday for 12 OECD member nations, Moody's said such pressure will be most evident in Italy, Japan and Spain but South Korea, Poland and Switzerland are also facing the impact.

The report said that with the latter three countries, in the absence of mitigating measures, aging populations will have a significant impact on their credit profiles due to lower economic and fiscal strength.

Moody's said that growth potential will drop to or below zero in some countries from the early 2030s unless an acceleration in productivity growth offsets the negative impact of shrinking populations. 

It also pointed out that aging can raise government debt burdens to high levels.