New York's main oil futures contract, light sweet crude for delivery in August, surged to 76.13 dollars per barrel -- the highest since early August 2006. Later Friday it stood at 75.79 dollars, down 13 cents from Thursday.

In London, Brent North Sea crude for September delivery eased four cents to 77.63 dollars per barrel after a peak of 77.98.

The August contract had struck 78.40 dollars on Monday, close to Brent's all-time high of 78.64.

"In our view, the oil market is highly overheated at present, irrespective of some news that has favoured prices," Commerzbank analysts said.

"The actual shortage is being overestimated by market players," they added in a research note.

Oil prices strengthened this week after official data that revealed an unexpected dive in stockpiles of US gasoline.

US motor fuel inventories fell by 2.3 million barrels in the week ended July 13, to 203.3 million barrels, leaving them 4.5 percent below their year-earlier levels, the US Department of Energy (DoE) said Wednesday.

Last week's drop in gasoline inventories compared with analyst forecasts for a rise of 700,000 barrels.

It came as gasoline consumption last week neared 9.71 million barrels per day, its second-highest level on record.