Asian stock markets were mixed Wednesday as investors remained cautious ahead of the outcome of the two major central bank meetings.

Japan's benchmark Nikkei declined 0.61 percent or 53.21 points to 8641.85 and South Korea's Seoul Composite declined 0.11 percent or 2.06 points to 1879.93. Chinese Shanghai Composite advanced 0.94 percent or 19.73 points to 2123.36 and Hong Kong's Hang Seng gained 0.12 percent or 23.57 points to 19820.38, while India's benchmark BSE Sensex gained 0.19 percent.

Market participants are waiting for the Federal Open Market Committee's (FOMC) statement on the monetary policy later in the day and the European Central Bank’s (ECB) monetary policy decision on Thursday when President Mario Draghi was expected to take fresh action, following his last week's pledge to do whatever it took to save the euro.

However, the Fed will want to wait for more data, on employment in particular, before considering any significant policy changes. Analysts expect the Fed to refrain from taking further policy action at the August FOMC meeting and see the September FOMC meeting as a more likely near-term decision point.

“Despite comments by the German Finance Ministry that it sees no need to give the ESM bailout fund a banking license, market hopes of ECB action Thursday remain in place, helping to give some support to markets and the EUR. However, the Fed is unlikely to deliver fresh stimulus measures following the conclusion of its two day meeting Wednesday,” said a note from Credit Agricole.

Chinese shares gained despite a disappointing manufacturing report as hopes of further easing offered support. The Industrial & Commercial Bank of China Ltd gained 1.57 percent and China Construction Bank advanced 0.76 percent in Hong Kong, while China Eastern Airlines Corp gained 0.49 percent in Shanghai.

The data released Wednesday by the China Federation of Logistics and Purchasing showed that official Purchasing Managers' Index (PMI) declined to 50.1 in July from 50.2 in June, the lowest reading since November 2011, when it hit 49 and also fell short of economists’ estimate of 50.4 reading.

Meanwhile, the HSBC China Manufacturing Purchasing Managers Index, a measure of the nationwide manufacturing activity, rose to a five month high of 49.3 in July from 48.2 in June. However, a reading below 50 indicates contraction.

Japanese shares ended lower as ongoing earnings season continued to influence the Tokyo market. Honda Motor plunged 5.72 percent as its fiscal year projection underwhelmed more optimistic market forecasts, the Wall Street Journal reported.

Mazda Motor Corp plunged 3.16 percent after announcing its first quarter loss and Komatsu Ltd. slumped 7.11 percent after reporting a decline in first quarter operating profit, while Panasonic Corp rallied 6.96 percent after reporting a seven-fold increase in its first quarter earnings.