HONG KONG - Asian stocks were mostly lower on Wednesday, weighed down by concerns over a slowdown in China's economy, while oil prices edged back up after big falls in New York.

Receding concerns over the eurozone debt crisis provided support for the euro, which continued its thrust upwards against the yen and greenback.

Tokyo fell 0.55 per cent, or 55.50 points, to 10,086.49 in the first trading day after ending Monday at its highest level since the quake-tsunami disaster in March last year.

The market was closed Tuesday for a public holiday.

Sydney fell 0.48 per cent, or 20.7 points, to 4,254.3, while Seoul fell 0.73 per cent, or 14.92 points, to 2,027.23.

Hong Kong shed 0.15 per cent, or 31.61 points, to 20,856.63 while Shanghai was flat, nudging 1.36 per cent higher to 2,378.20.

Concerns about China were raised on Tuesday when BHP Billiton said the country's demand for iron ore looked to be flattening as its economy slows, with exports weakening.

The comments by BHP's iron ore president Ian Ashby added to recent data that showed China's biggest trade deficit in February since records began, manufacturing activity plodding and inflation at its lowest since June 2010.

It also comes after China cut its growth target to 7.5 per cent for 2012 from last year's 9.2 per cent growth and 10.4 per cent in 2010.

Regional countries rely on fast-growing China to help drive their own economic expansion.

"Clearly any signs of a Chinese slowdown will manifest negatively," Christopher Gore, currency analyst at Go Markets, said in a note according to Dow Jones Newswires.

"However the question remains, are we witnessing a hard-landing scenario in motion or China's grand plan to promote sustainable long-term growth?"

The news weighed on US shares on Tuesday. On Wall Street the Dow index lost 0.52 per cent, the S&P 500 index fell 0.30 per cent and the tech-heavy Nasdaq was 0.14 per cent lower.

Oil prices nudged upwards on news of a huge fall in reserves in the United States.

The cost of the black gold has been fuelled by the ongoing standoff between Iran and the West over Tehran's nuclear programme, which Washington and its allies claim is being used to build a bomb.

New York's main contract, light sweet crude for delivery in May, rose 65 cents to US$106.72 (S$134.60) in the afternoon and Brent North Sea crude for May advanced 31 cents to 124.43.