Asian stocks struggled to keep their gains on Wednesday as a renewed slide in Chinese equities eclipsed upbeat data from the world's second-biggest economy, while the euro slipped ahead of a Greek parliamentary vote on austerity measures.

Investors also awaited congressional testimony by the US Federal Reserve chief later in the session.

Financial spreadbetters predicted European bourses would get a lift from Wall Street's gains, with Britain's FTSE 100 seen opening up as much as 0.3 per cent, Germany's DAX 0.4 per cent higher, and France's CAC 40 was expected to tack on 0.5 per cent.

MSCI's broadest index of Asia-Pacific shares outside Japan was slightly lower in afternoon trade as Chinese shares skidded, with Shanghai's benchmark composite index down 4.2 per cent, and the CSI300 index of the largest listed companies in Shanghai and Shenzhen falling 4.6 per cent.

China GDP

China's second quarter gross domestic product grew an annual 7.0 per cent, steady with the previous quarter and slightly better than analyst forecasts. Fixed-asset investment and industrial output growth also beat economists' forecasts.

Further stimulus is still expected after the quarter ended with a savage correction that shaved about 30 percent off share market value since last month, before Beijing's support steps stemmed the freefall for a while.

"Stock investors at present care more about what the government policy towards the market is, whereas the connection between the economy and the market has somehow loosened," said Zhang Qi, senior stock analyst at Haitong Securities in Shanghai.

Japan's Nikkei stock index ended up 0.4 per cent, after the BOJ kept monetary policy steady as expected and mostly maintained its upbeat inflation forecasts even as it cut its growth outlook on soft exports and household spending.

Spotlight on Greece

Later on Wednesday, Greece will take the spotlight as Athens will vote on a sweeping austerity package to secure the funding it needs to stem its fiscal crisis and remain in the euro zone.

Congressional testimony by Federal Reserve Chair Janet Yellen later in the session will be closely monitored for any further hints regarding the timing of a U.S. interest rate hike, particularly after a surprise fall in U.S. retail sales on Tuesday.

Core retail sales slipped 0.1 per cent, much worse than economists' forecasts for a 0.4 per cent rise.

The unexpected drop backed the view that the Fed might hold off on hiking rates, which gave Wall Street a lift. All three major indexes ended higher.

"People are not taking any aggressive positions ahead of Yellen. Some people are buying the dollar on dips," said Kaneo Ogino, director at foreign exchange research firm Global-info Co in Tokyo.

The upbeat Chinese data initially reassured investors and pushed up Treasury yields, which in turn lifted the dollar. The yield on benchmark 10-year notes was last at 2.404 per cent, up from its US close of 2.399 per cent on Tuesday.

The dollar ticked up about 0.1 per cent on the day to 123.45 yen, while the euro edged about 0.1 per cent lower to $1.0995.

Against the yen, the euro was buying 135.74 yen, down about 0.1 per cent on the day.

Crude futures were higher after it became apparent that a nuclear deal between Tehran and six global powers will not immediately remove sanctions placed on Iranian crude exports.

US crude was up about 0.2 per cent at $53.12 a barrel, while Brent added 0.2 per cent to $58.65

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