Oil prices fell more than a dollar today amid concerns over the ailing US economy.
US light crude for April delivery was down 68 cents at $101.16 a barrel by noon. London Brent crude was 62 cents down at $99.48.
But oil was supported by a weak dollar and expectations Opec will not change oil output when it meets this week in Vienna.
Comments from Opec members at the weekend suggested the producer group will not change output, rebuffing calls from the US to pump more oil to cool record prices of more than $100 a barrel.
Tensions in the Middle East, South America and Nigeria lent support to prices.
Opec members Venezuela and Ecuador sent troops to their borders with Colombia after Colombia bombed rebels inside Ecuador.
In Nigeria, attackers blew up a police houseboat on Bonny Island, an oil and gas export hub in southern Niger Delta. A fall in the US dollar to record lows against a basket of currencies also helped underpin the market.