World oil prices turned weaker on Thursday as trader concerns eased over a tropical storm in the US Gulf Coast where many American oil rigs and platforms are based, dealers said.
New York's main contract, light sweet crude for delivery in September, dipped 44 cents to 75.37 dollars per barrel in electronic deals before the official opening of the US market.
In London, Brent North Sea crude for September delivery lost 26 cents to 76.63 dollars per barrel in electronic trading.
Crude futures had spiked on Wednesday as traders fretted over the threat of hurricanes in the US Gulf of Mexico. Oil prices reached 77.47 in London and 76.50 in New York, both the highest levels since July 18.
"Crude oil futures were lower after Tropical Storm Chris weakened and according to latest forecasts is no longer expected to turn into the season's first hurricane that would have posed a real danger to oil and gas infrastructure in the Gulf of Mexico," Sucden analyst Michael Davies said.
According to the latest update from the US National Hurricane Center, the storm was "weakening in a hurry" and was not expected to reach hurricane strength.
Wednesday's price gains also followed news that US crude oil and gasoline reserves fell last week and as headlines suggested no let-up in the Israeli-Lebanese crisis.
"Fighting in the Middle East continues, as the major world powers are still failing to deter Israel from further air strikes and military assaults on Lebanon," Davies added.
"The much hoped ceasefire earlier this week failed to materialize with no diplomatic solution to the problem and Israeli jets continued their heavy bombardment of Lebanon."
Israel launched fresh air strikes on Beirut on Thursday after a lull of several days, as the world's Muslim nations expressed outrage at international "double standards" over the three-week-old offensive.
Concerns that fighting in the area might spark a wider conflict in the Middle East caused oil prices to hit to all-time highs above 78 dollars last month.
Elsewhere, traders remained mindful of the news flow from Nigeria, Africa's biggest crude producer, where output has been slashed by around 675,000 barrels per day, or 26 percent, by rebel attacks and a pipeline leak.
Oil market participants also kept on eye on Iran, which is the world's fourth-biggest crude producer.
The Islamic republic is facing a UN deadline to halt uranium enrichment by August 31 or have sanctions imposed. Traders fear sanctions might lead to severe disruptions to global oil supplies.
