Asian shares tumble on global economy doubts

European shares were also set to fall, while investors shifted to assets seen as safer during volatile times, including the yen.

Sentiment was hit by data on Tuesday showing China's exports in April fell more steeply than expected from a year earlier, casting fresh doubt on the prospects for recovery in the world's third largest economy. Imports also dropped.

Hopes of a recovery in China on the back of big government spending had fueled a surge in equity markets from lows in early March, as investors bet on a turnaround in the global economy.

"Exports are still falling, and the future of the world economy remains uncertain. It's really hard to be optimistic about China's trade prospects," said Qi Jingmei, an economist with the State Information Center in Beijing.

The MSCI index of Asia-Pacific stocks outside Japan <.MIAPJ0000PUS> lost 1.8 percent as of 0625 GMT (2:25 a.m. EDT).

That marked the second session of losses for an index that just on Monday had hit its highest level since early October. Still, it is up about 50 percent since early March.

Japan's Nikkei average <.N225> fell 1.6 percent, retreating from its highest close in six months on Monday.

The declines come as debate about the outlook for the global economy is confounded by the mixed nature of recent reports.

Optimists pointed to a survey from the Organization for Economic Co-Operation and Development on Monday that noted the pace of the decline in the world's major industrialized and emerging economies was easing.