(Reuters) - Asian shares fell Thursday as investors awaited manufacturing data from China later in the session for clues about whether Beijing would be prompted to take more stimulus action.

MSCI's broadest index of Asia-Pacific shares outside Japan <.MIAPJ0000PUS> inched down 0.1 percent, with Australian shares <.AXJO> easing 0.2 percent and South Korean shares <.KS11> falling 0.5 percent.

Japan's Nikkei stock average <.N225> opened down 0.6 percent after jumping to a 4-1/2 month high on Wednesday. .T

European shares gained on Wednesday as the Bank of Japan launched fresh stimulus to support its economy following last week's aggressive easing by the U.S. Federal Reserve, while U.S. stocks rose on data showing U.S. home sales rising in August to their highest in more than two years.

But investors have become wary of the uncertainty over whether highly indebted Spain will seek a bailout to ease its fiscal strains, as well as global growth slowdown which prompted central banks into action.

With major central banks around the world stepping up their efforts to bolster growth, investors focused on the HSBC Flash China manufacturing purchasing managers index, the first key data for September which sheds light to the state of the world's second-largest economy.

The Flash PMI edged slightly higher in September, rising from 47.6 to 47.8, the Financial Times reported Wednesday night. The figure shows that the sector is still contracting, but at a slower pace than previously. China's PMI has been falling since July and thus remained below the 50 boom-or-bust level for 11 straight months.

"If it continues the downward slide, we may see a case of where bad data is good for markets as the Chinese central bank may need to get involved in the liquidity injection bonanza, giving the AUD and NZD a boost against the USD," Neal Gilbert, currency strategist at GFT Forex in New Jersey, said in a note.

The euro steadied around $1.3052, bouncing from Wednesday's low of $1.29931, while the dollar slipped back from a one-month high against the yen of 79.23 touched on Wednesday after the BOJ's move, and was last trading at 78.37.

Reflecting an improved market sentiment after a round of monetary easing, the CBOE Volatility index <.VIX>, a gauge of expected volatility in the Standard & Poor's 500 index <.SPX>, fell on Wednesday to levels near a five-year low hit in mid-August.

Spain's reluctance to seek a bailout, which is conditional to triggering the European Central Bank's bond-buying scheme, kept demand solid for safe-haven German Bunds, but Spanish yields will likely fall sharply at Thursday's bond auctions.

Madrid will seek to raise up to 4.5 billion euros in three-year and 10-year bonds, after completing smooth sales of bills earlier in the week.

"Markets are still riding the Fed stimulus, albeit with less conviction," said Barclays Capital analysts in a note.

"There are tentative signs of a loss of short-term momentum in the euro risk trade following concerted central bank activity ... Investor optimism may be tempered in the short term by poor macro momentum and the potential for eurozone political volatility," they said.

Germany's ruling party proposed only limited bank supervisory power for the ECB on Wednesday, highlighting the differences over the speed and shape of oversight reforms and raising worries about the European policymakers' long-term debt-crisis management ability.

After weeks of talks, Greece said it has secured the blessing of its lenders on an additional chunk of spending cuts in its austerity plan, a senior government official said on Wednesday, bringing the crisis-hit country closer to a winning further aid.

Oil prices fell more than 3 percent on Wednesday on comments from top producer Saudi Arabia that it would take action to keep prices in check, as well as on U.S. data showing crude stocks climbed far more than expected.

Early on Thursday, U.S. crude eased 0.1 percent to $91.90 a barrel while Brent also inched down 0.1 percent to $108.08.