Brent slipped below $104 per barrel on Thursday as investors remained worried about fuel demand after a series of weak economic data, although losses were capped by hopes for more U.S. stimulus measures to support growth.
Prices also fell after U.S. government data showed an unexpected rise in domestic crude stockpiles last week, stoking oil demand worries.
Brent crude had fallen 52 cents to $103.86 per barrel by 0452 GMT, while U.S. crude was down 48 cents at $88.49.
"The risk is to the downside and I think we will need some sort of catalyst to change the direction of Brent prices, be it either the current demand or supply outlook," said Ric Spooner, chief market analyst at CMC Markets in Sydney. "People are looking towards the possibility of quantitative easing by the U.S. as a weaker dollar will be supportive of commodity prices."
Data showing the biggest drop in more than a year in U.S. single-family home sales in June, reflecting a sluggish recovery for the housing market, reinforced expectations that the Federal Reserve would act to adopt more quantitative easing to support the economy.
Geopolitical risks also remained a focus amid fears Syria could resort to chemical weapons in its efforts to suppress the 16-month revolt against President Bashar al-Assad.
Oil prices were earlier supported after European Central Bank Governing Council member Ewald Nowotny said he could see grounds for giving the euro zone bailout fund a banking license that would increase its crisis-fighting firepower.
But ECB President Mario Draghi poured cold water on the idea, while legal problems could also prevent the central bank allowing its European Stability Mechanism rescue fund to tap liquidity operations.
DOWNBEAT GLOBAL OUTLOOK
Adding to the downbeat global economic outlook, South Korea's economic growth slowed more than expected in the second quarter and barely averted a decline, mainly thanks to a tumble in imports, deepening worries about the prolonged crisis in Europe, and slowing growth elsewhere.
German business sentiment dropped in July for a third straight month to the lowest level in more than two years, while British economic output shrank more than expected in the second quarter.
But borrowing costs in Spain, which is facing snowballing regional debts and a banking sector struggling to clean up bad loans, retreated slightly on Wednesday.
In China, nearly a quarter of companies in the country's export hub of Guangdong province lost money in the first five months of this year on faltering demand, rising costs and financing shortfalls, the official Xinhua News Agency reported.
A spokesman for the Ministry of Industry and Information Technology said on Wednesday that about 17 percent of China's industrial companies lost money in the first five months of 2012, below a 25 percent peak in the 2008/09 global financial crisis.
U.S. OIL INVENTORIES
U.S. crude oil inventories rose unexpectedly by 2.72 million barrels last week on sharply higher imports, defying forecasts for a modest drawdown of 700,000 barrels, data from the U.S. Energy Information Administration showed.
Crude imports rose 695,000 barrels per day to 9.59 million bpd, the highest since July 2011. Crude stocks at Cushing, Oklahoma delivery point rose 203,000 barrels to 46.49 million barrels.
Adding to geopolitical tension, Western powers have been calling for Syrian President Bashar al-Assad to be removed from power in the wake of a revolt against his regime, but they now fear he will fight to the end, raising the risk of sectarian warfare spreading across one of the world's most volatile regions.
Syria confirmed on Monday that it had chemical and biological weapons and said it would use them against external threats, prompting warnings from Washington and Moscow against using the arsenal.
"Prices rallied more than half a percent overnight on growing worries about the implications of the conflict in Syria," ANZ analysts wrote in a note on Thursday. "We may see some of the risk premium in oil rebuild."