TOKYO - The International Monetary Fund called on Asian economies to learn from Japan's experience and act early to cope with rapidly aging populations, warning that parts of the region risk "getting old before becoming rich".

Asia has enjoyed substantial demographic dividends in the past decades, but the growing number of elderly is set to create a demographic "tax" on growth, the IMF said in its economic outlook report for the Asia-Pacific region on Tuesday.

"Adapting to aging could be especially challenging for Asia, as populations living at relatively low per capita income levels in many parts of the region are rapidly becoming old," the report said. "Some countries in Asia are getting old before becoming rich."