Investors were also waiting for the release Wednesday of weekly crude oil stockpiles in the United States to gauge demand in the world's biggest oil consuming nation, analysts said.

New York's main contract, West Texas Intermediate (WTI) for May delivery eased 24 cents to $99.36 a barrel in mid-morning trade, and Brent North Sea crude for May dipped 30 cents to $106.51.

Kenny Kan, an analyst at CMC Markets in Singapore, said the temporary closure of the Houston shipping route lifted WTI prices.

The Houston Ship Channel was shut down after a weekend collision between a barge and a ship resulted in the spill of about 168,000 gallons (636,000 litres) of fuel oil into the waterway.

The closure disrupted supplies to refineries in the US Gulf Coast.

Kan said in a market commentary that "although the temporary closure of the shipping channel may not have a tangible impact on this week's crude inventories report, it has caused much volatility".

Brent prices continued to face downward pressure following weak manufacturing data in China, the world's second biggest economy.

British banking giant HSBC's flash purchasing managers index (PMI) for March for China's key manufacturing sector came in at 48.1, an eight-month low and down from 48.5 in February.

Any PMI reading below 50 indicates contraction while a figure above points to expansion.