Brent crude rises above $100 Oil prices have risen above the psychological $100 a barrel level for the first time in three weeks, spurred by mounting Iran tensions and a supply disruption and a strike among Norway's offshore oil and gas workers. The return to triple-digit oil prices comes only three weeks after oil prices fell below the key level as Tehran repeats the same threats it made in the first quarter about closing down the Strait of Hormuz, a key waterway for oil trade. The Brent benchmark, which jumped on Friday on the back of hopes of a resolution of the eurozone crisis, extended its rally on Tuesday to 10 per cent in a week. In afternoon trading in London, ICE August Brent rose over $2 hitting $100.17 a barrel. Brent later pared gains to trade at t $99.67 a barrel, up $2.33 on the day. The flare-up around Iran has taking most traders by surprise, forcing those holding bearish bets to cover their positions, further exacerbating the rally, analysts said. Iranian media on Monday reported that the country's national security committee had drafted a plan to "prevent passage of oil tankers carrying crude to the countries which had imposed sanctions" against Tehran. It is unclear whether Iranian government supports the plan, which had been mooted in the past. The surge in Iranian threat's comes days after the last European and US sanctions on the country's oil exports come in effect over the weekend. Oil traders believe the sanctions would knock down 400,000 barrels a day of Iranian sales, on top of the already 600,000-800,000 b/d that other sanctions have already disrupted. The loss of Iranian sales is tightening the oil market again even if Saudi Arabia continues pumping at a 30-year high of 10m b/d, according to industry sources familiar with Saudi's oil policy. July will mark the sixth consecutive month of Saudi production around the 10m b/d, according to industry officials. The tightness in the oil market was highlighted by the Brent front month contract moving higher than the following contract in September. The downward slope of the futures curve, known as "backwardation" was seen at the start of the week, showing high demand for oil for immediate delivery. The scramble for supplies as the Iranian sanctions kicked in at the start of the week has been exacerbated by the workers" strike in Norway, which has cut output by 13 per cent of capacity, according to some estimates. Norway is the world's fifth-largest oil export and its supplies affect particularly hard the Brent oil market. Meanwhile, agricultural commodities continued to rally on the back of expected crop damage caused by the extreme heat in the US. CBOT Front-month corn, or the July contract, rose above $7 a bushel for the first time since September last year, while the December contract, representing the new crop, jumped to $6.72 a bushel, almost reaching the contract-high of $6.73½ set in August 2011.