Crude oil prices rose in early Monday trading amid tensions in Ukraine, but fell again after Libyan protesters ended their occupation of an oil port.
The price of Brent crude futures briefly rose above $108 a barrel, but later fell back to $107.30.
Libya's state oil firm said the port of Zawiya and its refinery had reopened and were operating normally.
But pro-Russian militants are still occupying buildings in eastern Ukraine, ignoring a deadline to leave by Kiev.
EU foreign ministers are meeting to discuss new sanctions against Russia.
Brent crude oil was trading at $107.74 a barrel at 12:30 BST, up 41 cents or 0.4%, while West Texas Intermediate crude was trading little moved at $103.62.
Gas supply threat
Energy analysts say the crisis in Ukraine is unlikely to have a direct impact on global oil supplies. However, disruption to Europe's gas supplies is possible.
President Putin wrote to EU leaders last week saying that Russia would cut gas supplies to Ukraine if it did not pay its bills.
This could lead to a reduction of gas supplies to Europe - much of which comes via pipelines across Ukraine.
The European Union's Energy Commissioner, Guenther Oettinger, is expected to discuss this threat to gas supplies at Monday's meeting of EU foreign ministers.
Meanwhile, Libya's western Zawiya oil port resumed operations after protesters left the entrance to the facilities and the adjoining refinery has also restarted production.