WASHINGTON -- New research shows Asia's top powers have doubled defence spending in the past decade, spurred by the explosion in military expenditure by China.

The report was released Monday by the Center for Strategic and International Studies think-tank and found that while troop numbers have remained constant, overall spending has grown to $224 billion by 2011. Spending particularly accelerated in the second half of the decade.

The research covers China, Japan, India, South Korea and Taiwan, which account for some 87 per cent of Asia's defence spending.

China's share of the total spending has risen from about 20 per cent in 2000 to 40 per cent in 2011. Worldwide, only the United States spends more on defence.

The official Chinese figures that the report's authors used likely underestimate how much China actually spends.