Crude oil futures rose during early European trading hours on 7 March as worsening diplomatic relations between Ukraine and Russia fuelled supply fears.
The April Brent contract added 21 cents to $108.31 per barrel at 07:20GMT on the ICE exchange in London.
The April US crude contract rose 31 cents to $101.87 a barrel at 07:20 GMT in electronic trading on the New York Mercantile Exchange.
US President Barack Obama has pushed for a diplomatic solution to the Ukraine crisis in a telephone conversation with Vladimir Putin, but the stalemate continues after the Russian President insisted his action was triggered by Kiev's "illegitimate decisions" on the Russian-speaking Crimea region.
Obama told Putin in an hour-long talk that his government was taking steps in coordination with its European partners over Russia's violation of Ukraine's sovereignty, the White House revealed.
The two leaders spoke after regional Crimean lawmakers voted to adopt a resolution calling for secession from Ukraine and union with Russia, and set a 16 March referendum -- moves strongly condemned by the West.
Commerzbank Corporates & Markets said in note to clients: "Brent gained by nearly $1 during the course of trading yesterday to reach $108.5 per barrel, meaning that the oil market is reacting relatively calmly to the tensions that are once again escalating in the Crimean crisis. The prices of other commodities such as the platinum group metals and grains have risen considerably more sharply in recent days. To some extent this can be explained by the immediate consequences, though the low level of nervousness on the oil market is also the result of the price having already been trending sideways for months now.
"Evidently the market is comfortably balanced at present, and even the latest reports from Libya cannot knock it out of its comfort zone - apparently, the resumption of production at the El Sharara oil field will be further delayed, contrary to what had been thought mid-week, and there are no signs of the oil terminals in the east of Libya reopening either."
"The lower OPEC shipments are giving equally little cause for concern - according to consultant firm Oil Movements, they will be 400,000 barrels per day lower in the four weeks to 22 March than in the preceding four-week period - since the decline is attributable to seasonally lower demand in Asia. Given that spring is just around the corner now, the low ARA gasoil stocks are also no reason to worry, even though they are at their lowest level for this time of year since 2008. The situation will have to get a great deal worse to unsettle the oil market."