Oil prices hit four-month highs on Friday after the Federal Reserve launched a new round of economic stimulus aimed at lifting growth in the world\'s largest crude consumer. The market also won strong support from ongoing geopolitical tensions in the Middle East. In London morning deals, Brent North Sea crude for delivery in November soared to $117.95 a barrel, touching the highest level since early May. New York\'s main contract, West Texas Intermediate (WTI) or light sweet crude for October, surged to a similar peak at $100.42 a barrel. Global markets rallied after the Fed on Thursday said it would start a third programme of purchasing $40-billion per month in mortgage-backed bonds, known as quantitative easing (QE3). The Fed added that it would continue with the scheme until it saw substantial improvement in the jobs market. The US central bank also pledged to keep its benchmark interest rate at ultra-low levels until at least mid-2015. \"The Fed\'s announcement has caused crude oil prices to climb to multi-month highs,\" said Commerzbank analyst Carsten Fritsch. While the announcement had been expected, dealers cheered the fact that the central bank said it will continue with the policy until it feels the economy is strong enough. This week, crude futures have also jumped higher in the wake of violent protests touched off by a film mocking Islam that was posted on the Internet. Washington\'s ambassador to Libya was killed during a mob attack in the city of Benghazi on Tuesday. Demonstrations have spread across the oil-rich Middle East and further afield, including to Bangladesh, Iran, Iraq, Israel, the Gaza Strip, Kuwait, Sudan and Tunisia. \"Supply risks are lending psychological support\" to global oil prices, said analyst Fritsch. \"Renewed anti-American protests are expected in Arab countries today after the US ambassador was killed in Libya two days ago and the US embassy in Yemen was stormed yesterday. \"This region, which is so crucial to the supply of oil, is thus far from stable, something that is likely to give rise to a lasting risk premium,\" he added. Added to the volatile geopolitical backdrop, traders remain deeply concerned over key crude producer Iran\'s nuclear ambitions. On Thursday, the UN atomic agency\'s board approved with a crushing majority a resolution criticising Iran brought by world powers that was also aimed at dissuading Israel from military action. The resolution expresses \"serious concern that Iran continues to defy\" UN Security Council resolutions for it to suspend uranium enrichment, a process which can be used for peaceful purposes but also in a nuclear weapon. It also highlights the International Atomic Energy Agency\'s complaint that activities at the Parchin base near Tehran, where it suspects nuclear weapons research took place, would \"significantly hamper\" inspectors -- should Iran let them visit. Tehran has insisted that its expanding atomic programme is for peaceful purposes.