Asian shares caught a tailwind on Wednesday after upbeat German economic data powered gains in US and European markets, while the safe-haven yen skidded as investors' mood turned positive.

MSCI's broadest index of Asia-Pacific shares outside Japan was up 2.5 per cent by 0250 GMT, with gains across all the major indices that were open.

Japan's Nikkei soared 5.7 per cent, on track for its biggest one-day rise since March 2011. In the previous session, it lost 2.4 per cent and wiped out its year-to-date gain.

Major Wall Street indices all logged gains of more than 2 per cent overnight.

European stocks also had a banner day on news Germany's imports and exports hit record highs in value terms in July.

Chinese shares rose late on Tuesday after digesting a bigger-than-expected drop in imports. The trade data raised fears that China's slowdown could be sharper than many had expected, which in turn raised hopes that Beijing would muster more easing steps to prevent a hard landing.

The Shanghai Composite index climbed 1.7 per cent on Wednesday. Hong Kong's Hang Seng index added 2.7 per cent.

"With many markets having been sold off heavily over recent weeks, today's rally, like the US last night, represents a speculative bounce," said Angus Gluskie, managing director of White Funds Management in Sydney.

"The market will remain susceptible to a return of negativity until we see signs of some improvement in the original causes of weakness, which were predominantly Chinese growth concerns," he said.

The dollar put in a mixed performance, slipping slightly against a basket of six rival currencies to 95.945, and against the euro to $1.1191.

But the greenback firmed about 0.5 per cent against the yen to 120.25 as the improved market mood sapped some of the appeal of the perceived safe-haven Japanese currency.

The euro also gained on the yen, rising 0.3 per cent to 134.56.

Crude oil futures remained steady but at low levels on lingering concerns about a global supply glut.

US crude rose 0.2 per cent to $46.15 ahead of weekly crude inventories data due from industry group American Petroleum Institute later in the session.

Brent crude rose 0.4 per cent to $49.74, after jumping 4 per cent the previous session following upbeat German economic data. – Reuters