TOKYO: Asian shares fell on Tuesday as crude oil prices slid on rekindled oversupply fears and after downbeat manufacturing data raised concerns about sluggish global economic growth.

MSCI's broadest index of Asia-Pacific shares outside Japan was down 0.4 percent.

Japan's Nikkei slipped 0.5 percent as investors locked in profits after two straight days of big gains following the Bank of Japan's decision to introduce negative interest rates late last week.

US crude oil was down about 1.8 percent at $31.06 a barrel after skidding as much as 7 percent overnight, pressured by weak economic data from China, a US forecast for mild weather and doubts that suppliers would be able to agree on steps to address the global supply glut.

Despite the declines, US crude is still nearly 19 percent above the more than 12-year low of $26.19 hit in mid-January.

"(Prices) have just come back to reality a bit, although they are holding water above $30 a barrel," said Ben Le Brun, market analyst at Sydney's OptionsXpress, pointing to concern over rising oil supplies and weaker economic data.

Brent April crude futures slipped 1.5 percent.

Oil faced fresh pressure from Chinese manufacturing data for January released on Monday showing the fastest pace of contraction since 2012.

The Australian dollar was down about 0.4 percent at $0.7088, though it held above its recent seven-year trough of $0.6827.

As expected, the Reserve Bank of Australia held interest rates steady at a record low of 2.0 percent, where they have stood since May 2015. Although the bank was hopeful on growth prospects, it reiterated that there was scope for a further cut if needed to support the economy.

The greenback slipped about 0.3 percent against its Japanese counterpart to 120.67 yen, but remained underpinned by the BOJ's surprise move on Friday to adopt negative interest rates.

Markets had a muted reaction to results of Iowa's Republican presidential nominating primary election, in which U.S. Senator Ted Cruz beat billionaire Donald Trump. On the Democratic side, former Secretary of State Hillary Clinton was in a virtual tie with rival Bernie Sanders.

Wall Street marked modest losses on Monday, after January surveys of global factory activity on Monday showed the new year began much as the old one ended, with too much capacity chasing too little demand.

Global manufacturing expansion accelerated slightly but remained weak at the start of 2016 as faster growth in developed markets failed to offset a contraction in emerging economies.

U.S. economic data showed manufacturing activity contracted in January for a fourth straight month as factories grappled with a strong dollar and lower oil prices forced energy firms to further cut spending, but the pace of the decline appeared to be slowing.

The euro was up about 0.2 percent at $1.0909, mired in recent ranges, its gains limited by the disappointing euro zone manufacturing data as well as comments from European Central Bank President Mario Draghi.

The central bank head stressed the risks facing the euro zone and reiterated the ECB was ready to review its monetary policy stance in early March.