The Bank of Korea says the foreign exchange reserves of South Korea, Japan, China and Taiwan have doubled in the past three years. The four Asian countries rank within the top four in terms of the amount of foreign exchange reserves in the world.

The central bank said Tuesday that the increase stemmed from efforts by the four nations to protect the foreign exchange rate from mounting appreciation pressure that stems from increasing influx of foreign currency. The bank cited that such an inflow of foreign currency originated from the four Asian nations’trade surplus and attraction of foreign direct investment.

According to the central bank, Japan, the number one foreign exchange reserve holder in the world, saw its foreign exchange reserve sharply rise to some 840 billion U.S. dollars as of last month, double compared to the 402 billion dollars in 2001.

Meanwhile, South Korea, ranking fourth, is nearing 200 billion dollars in foreign exchange reserve after witnessing a significant increase from 102.8 billion dollars in 2001 to 196 billion dollars last week.