Oil prices edged back on Friday from four-week highs above $36 a barrel, but were supported as a build in US crude stocks did little to ease concerns about supplies, traders said.
Benchmark US light crude for March was trading 12 cents lower at $35.88 a barrel after trading as high as $36.10 late on Thursday, marking the highest since January 20 when prices hit $36.37 a barrel.
April was down four cents at $34.60. "It has been up eight days in a row, so it's a logical point to take a little profit," a broker in New York said. April Brent crude on the International Petroleum Exchange was up 33 cents at $31.10 a barrel, catching up on the firmness in US prices on Thursday.
Crude futures bounced from sell-off on Thursday prompted by a higher-than-expected rise in US crude stocks.
The weekly Energy Information Administration (EIA) stocks data showed a 4.9-million-barrel increase in crude stocks, against market forecasts for a 1.13-million-barrel build for the week ended February 13.
Prices recovered when the market realised a large concentration of the crude build was on the US West Coast, deemed as isolated geographically.
Analysts said the market's firmness could be attributed to the government data that also showed crude stocks fell in the Midwest, which includes the Cushing, Oklahoma, delivery point for oil traded on the New York Mercantile Exchange.
"Despite this large crude build there was actually a draw of 1.1 million barrels in PADD 2 (Midwest) which is what may be getting our price up," said Katherine Spector, energy strategist at Deutsche Bank.
US distillates stocks, which include heating oil, showed a steep decline of 5.8 million barrels to 112.5 million barrels, on strong demand, EIA data showed.
Despite scepticism over Opec's commitment to output cuts the market kept a wary eye over the cartel's moves.
"Prices have been up eight straight days since the Opec announcement," the New York broker said, adding the market would be watching closely to see if Opec members would comply with quotas at a time when prices are high.
He said the strong euro, which had surged as much as 30 percent against the US dollar since November 2002, meant current crude prices were the equivalent of $27 a barrel for buyers using the European currency, within the range of Opec's targeted price band.
Opec decided last week to cut production by one million barrels per day from April 1 and to move immediately to curb 1.5 million bpd of output over current quotas to stop stocks from building too heavily in the second quarter.