"Disruptions to Iranian supply would drive oil prices significantly higher," financial services firm Morgan Stanley said in a report.
Traders are also closely watching the latest U.S. crude inventory figures. The American Petroleum Institute said late Tuesday that crude inventories rose 148,000 barrels last week while analysts surveyed by Platts, the energy information arm of McGraw-Hill Cos., had predicted an increase of 1 million barrels.
Inventories of gasoline fell 1.5 million barrels last week while distillates dropped 2.9 million barrels, the API said.
The Energy Department's Energy Information Administration reports its weekly supply data — the market benchmark — later Wednesday.
In other Nymex trading, heating oil rose 0.9 cent to $3.13 per gallon and gasoline futures added 0.9 cents to $2.72 per gallon. Natural gas slid 1.3 cents at $3.73 per 1,000 cubic feet.
Alex Kennedy in Singapore and Tarek El-Tablawy contributed to this report.
Copyright 2011 The Associated Press.