World oil prices rose further Friday ahead of US economic growth data, a day after climbing on easing concerns over the eurozone debt crisis, analysts said. A day after winning support from European Central Bank president Mario Draghi\'s pledge to \"do whatever it takes to preserve the euro, crude futures extended gains before Friday\'s publication of second-quarter US growth data. Brent North Sea crude for delivery in September gained 45 cents to $105.71 a barrel in London midday deals. New York\'s main contract, light sweet crude for September, won 18 cents to $89.57 a barrel. \"Price increases on the oil market are being triggered at present largely by external factors such as yesterday\'s statements or supply-side risks,\" said Commerzbank analyst Carsten Fritsch. Draghi\'s rousing vow of support for the European single currency issued inspired oil traders to re-enter the market. Dutch bank ABN Amro said tensions in the crude-producing Middle East \"could remain the most important driver for oil prices\" in the third quarter. \"We expect volatility to remain high but prices to trade within small ranges,\" it said in a report. Oil prices have risen for much of the week, also on hopes of central bank stimulus that helped to offset data showing an increase in US crude stockpiles. Crude futures have also won support this week on encouraging Chinese manufacturing data. But they plunged by more than $3.50 on Monday on the eurozone debt woes.