World oil prices soared in volatile trading las Monday on short-term supply uncertainties and a question mark over whether OPEC producers would soon open their taps. International benchmark Brent crude futures traded on London's International Petroleum Exchange (IPE) stood 85 cents a barrel up, while U.S. light crude was up $1.20. Prices are at their highest since the Organization of the Petroleum Exporting Countries (OPEC) agreed in March to raise output by seven percent. Traders said a strike affecting production in Norway, the world's second largest exporter, combined with continued uncertainty over OPEC's next production move led to Monday's buying spree.