Brent crude oil for April spiked up $8.54 a barrel to a peak of $119.79 before easing to around $114.40 by 1450 GMT. US crude futures for April rose as high as $103.41. They were up $1.70 at $99.80 at 1450 GMT.
Unrest in the world's 12th-biggest exporter has cut at least 400,000 barrels per day from Libya's 1.6 million bpd output, according to Reuters calculations.
ENI Chief Executive Paolo Scaroni said Libyan output had fallen much more dramatically, estimating it was putting 1.2 million barrels per day less into the market.
Eastern areas holding much of Libya's oil have slipped from the control of Muammar Qaddafi.Goldman Sachs said the spread of unrest to another producing country could create severe oil shortages and require demand rationing. "The market cannot accommodate another disruption, in our view, with the problems in Libya potentially absorbing half of OPEC's spare capacity," analyst Jeffrey Currie said in a research note.
Reuters market analyst Wang Tao said technical charts showed Brent could be on course for a rise to $158 per barrel in 2011, well above its 2008 high of $147.50, while he expected US crude to touch $159 per barrel.
Traders and analysts have said the loss of virtually all Libya's production is particularly serious because it is high quality, easy-to-refine oil in contrast to the heavier crude often associated with the Organization of the Petroleum Exporting Countries.
"Saudi is willing and capable of supplying oil of the same quality, either Arab extra light or through blending," one oil industry source said. "OPEC stipulates that it is able to supply all types of oil if needed," the source added. "There is no reason for the price to go higher."
Weekly US oil inventory data from industry group API showed Wednesday that petroleum stocks had risen by 163,000 barrels last week, after analysts polled by Reuters had forecast a bigger rise of 1.2 million barrels.
Distillate inventories fell a less-than-expected 534,000 barrels and gasoline supplies fell 1.6 million barrels, API data showed, bucking analyst expectations for a rise.
The US Energy Information Administration's weekly inventory data were due to be released later.
