Asian shares hit a four-month high on Tuesday after dovish comments from Federal Reserve Chair Janet Yellen and China's official PMI survey showing the manufacturing sector managed to continue expanding in March.

MSCI's broadest index of Asia-Pacific shares outside Japan rose by up to 0.4 per cent to reach its highest level since early December. European shares are expected to gain, with both Britain's FTSE and France's CAC seen rising 0.3 per cent.

The Nikkei failed to match other indexes, falling 0.2 per cent as the Bank of Japan's tankan survey showed Japanese companies cautious on the economic outlook as a three-per centage-point sales tax hike took effect on Tuesday.

Global shares were also supported by Fed chair Janet Yellen reinforcing the need for an "extraordinary" commitment to support the US economy, seemingly tempering expectations of a sooner-than-expected start to the rate-hike cycle.

In her first public speech since becoming Fed chair two months ago, Yellen said there remains "considerable" slack in the economy and job market.

"It seems like she expressed her own dovish ideas. There's nothing really new and the outlook of the Fed's policy has not changed that much but the markets like her remarks," Makoto Noji, senior strategist at SMBC Nikko Securities.

China's official Purchasing Managers' Index increased to 50.3 in March from February's 50.2, staying above 50, which indicates expansion.

While the PMI figure alone is hardly enough to dispel concerns of a slowdown in China, investors' belief in China has improved in recent weeks as they expect Beijing to adopt a stimulus plan to meet its growth target.

Emerging markets, which suffered a sharp selloff earlier this year on concerns about a turn in Fed policy, slowdown in China and political instability in some countries, are showing signs of life.

MSCI's emerging market index hit a three-month high, having outperformed S&P 500 since late March.

Rising risk appetite undermined lower-risk assets that had attracted safety bids last month at the height of the Ukrainian crisis.

Gold hit a seven-week low of $1,278.34 per ounce, despite Yellen's dovish comments while the yen also slipped to a three-week low against the dollar of 103.44 yen and a nine-month low against the risk-sensitive Australian dollar at 95.75.

The euro bounced back against the U.S. dollar to fetch $1.3774 even as softer-than-forecast inflation numbers put more pressure on the European Central Bank to act against the threat of deflation.

Euro zone inflation dropped to 0.5 per cent in March, its lowest level since November 2009, having been in the ECB's "danger zone" of below 1 per cent for six consecutive months.

However, not many market participants expect the ECB to act at its policy meeting on Thursday, partly because of comments from ECB council member and Bundesbank President Jens Weidmann on Saturday.

Weidmann said that the euro zone is not in a deflationary cycle and that the ECB should not over-react to a slowdown in inflation caused largely by cyclical factors which should prove temporary.

The immediate focus is on a barrage of manufacturing data in Europe, which is expected to show output in most countries to have stayed flat or weakened slightly in March.

Crude futures were off three-week highs following news Russia was withdrawing some troops from the Ukrainian border. U.S. crude futures stood at $101.41 per barrel, off Friday's high of $102.24.-Reuters