Asian stocks mostly gained on Tuesday and the Japanese yen rallied to a fresh eighteen-month high as investors grew doubtful about global central banks' ability to boost growth through aggressive policy easing.

    On Tuesday, Australia's shares climbed and its dollar falling after the Reserve Bank of Australia cut interest rates unexpectedly. The RBA cut its benchmark rate by 25 basis points to a record low 1.75 percent, noting that inflation data are unexpectedly low and that it is less concerned by the risk low rates pose to the housing market. 

    In the wake of the decision, the benchmark ASX 200 ended up 2.11 percent, or 110.83 points, at 5,353.80, compared with gains of around 0.55 percent before the decision. The Australian dollar dropped to as low as $0.7553 after the decision, from levels a tad above $0.77 before the announcement.

    Meanwhile, regional markets largely shrugged off a disappointing survey on China's manufacturing sector. Hong Kong's Hang Seng Index dropped 1.45 percent by 3:37 p.m. HK/SIN time, extending losses after the disappointing data. But on the mainland, shares extended gains, with the Shanghai Composite tacking on 1.87 percent, or 54.87 points, to end at 2993.20, and the Shenzhen Composite added 2.94 percent, or 55.04 points, to close at 1929.03. 

    South Korea's Kospi index added 0.42 percent, or 8.26 points, to end at 1986.41. Japan's stock market is closed for the Golden Week holidays.  Elsewhere, financial spreadbetters expect stock markets in Britain, Germany and France to open broadly steady to slightly higher on Tuesday.

    The dollar set a fresh 18-month low versus the yen on Tuesday, as the yen pushed higher in a holiday-thinned market with one Singapore-based trader saying there appeared to some speculative yen buying. The dollar was trading at the day's lows, down 0.5 percent to 105.9 yen JPY=, its lowest level since October 2014.