Brent oil on Wednesday surpassed $90 per barrel to strike the highest level for more than seven years, rattled by geopolitical tensions in Ukraine and supply concerns in the Middle East.

European benchmark Brent North Sea crude rallied as high as $90.42 in afternoon London trade, attaining a level last seen in October 2014.

The contract later stood at $90.23, up 2.3 percent from Tuesday.

"This has been coming for a while and even over the last week when prices were easing a little, there was little hope that it would lead to any kind of significant pullback," OANDA analyst Craig Erlam told AFP.

"With the price now above $90 and gathering momentum once more, it may just be a matter of time until it's flirting with $100.

"The fundamentals (of supply and demand) remain bullish for oil prices and the prospect of a Russian invasion of Ukraine will only increase the risk premium."