Brent oil prices jumped more than 2% on Tuesday due to an oil workers strike in Norway and to tensions in the Middle East, while fear of crop destruction from a drought in America's grain belt drove corn up for a second day. A buying frenzy developed in coffee after the premium arabica grade, sought by leading coffee chains, pierced key bullish points on the price chart, sending it to a four-week high. The Thomson Reuters-Jefferies CRB index, a