Oil prices climbed higher above $100 a barrel Friday on renewed concerns about tensions in Ukraine.
By early afternoon in Europe, benchmark U.S. crude for June delivery was up 43 cents to $100.69 a barrel in electronic trading on the New York Mercantile Exchange. On Thursday, the Nymex contract fell 51 cents.
Brent crude, a benchmark for international varieties of oil, was up 59 cents to $108.63 on the ICE Futures exchange in London.
Pro-Russian insurgents in eastern Ukraine are planning a referendum on independence over the weekend, in apparent defiance of a call by Russian President Vladimir Putin to put off the vote.
Traders worry Russian energy exports could be interrupted if further instability in Ukraine results in stronger Western sanctions against Russia.
The prolonged closure of major export terminals controlled by militias in eastern Libya also supported oil prices.
"Libya's two most important oil terminals, Ras Lanuf and Es Sider, will remain shut for the foreseeable future which is likely to continue to severely hamper the supply of oil," said analysts at Commerzbank in Frankfurt in a note to clients.
In other energy futures trading in New York:
— Wholesale gasoline added 1.9 cents to $2.924 a gallon
— Heating oil gained 1.88 cents to $2.939 a gallon.
— Natural gas rose 0.1 cent to $4.573 per 1,000 cubic feet.