Oil prices were little changed Tuesday after jumping above US$66 a barrel in the previous session on worries about gasoline supply.
Light, sweet crude for June delivery was flat at US$66.27 a barrel in Asian electronic trading on the New York Mercantile Exchange midmorning in Singapore. It had gained as much as 5 cents in early trade. On Monday, the contract climbed US$1.33 to US$66.27 per barrel.
Worries that violence could rise in Nigeria ahead of the inauguration of a new president supported prices. Nigeria is one of the world's largest crude producers, and attacks on oil installations have become an almost daily occurrence following elections there last month.
"Profit-taking may trim prices for a while," said Koichi Murakami, an analyst with brokerage Daiichi Shohin. "But later, I think they will be supported by the Nigerian concerns."
Attackers in Nigeria vandalized an oil installation run by Total SA, the company said Monday. No injuries, kidnappings or production cuts were reported.
Traders are also worried about gasoline supplies heading into the peak Northern Hemisphere summer driving season which kicks off this weekend in the U.S.
The U.S. Energy Information Administration reported last week that domestic gasoline inventories - while increasing to 195.2 million barrels for the week ended May 12 - are still well below the average for this time of year.
The market was also eyeing the U.S. government's release of its updated hurricane outlook this week.
Weather has played an increasingly important role in oil prices in recent years. Prices surged to US$70 a barrel for the first time in 2005 as Hurricane Katrina ravaged the Gulf of Mexico Coast. They broke above US$78 a barrel in July 2006 on worries of another bad storm season, and then sank to US$60 a barrel when those expectations weren't met.
Heating oil futures were also flat at US$1.9509 a gallon (3.8 liters) while natural gas prices rose a tad to US$7.919 per 1,000 cubic feet.