Some analysts said the reasons for the recent spike in prices were speculation and higher demand for specific refined products, notably diesel.

“We’re not in an energy crisis, we’re not short of oil, we’ve got a refinery shortfall,” said John Hall, managing director of the consultancy John Hall Associates in Horsham, Britain. He blamed speculators and certain banks for “talking up” the crude price and seeking to benefit from it.

The market appears to be well supplied with crude oil, he said, citing as an example reports that Iran has been unable to sell some of its heavy crude. The main issue is a shortage of diesel, distillate and similar products because of refinery constraints and higher demand from power stations in Asia and the Middle East, Mr. Hall said.

These factors make it harder to predict where the price of oil will go. But further out, Mr. Hall said, demand and price will fall as Western consumers change their behavior as a result of higher prices, as more nuclear power comes on stream and as the effect of the removal of subsidies in Asia is felt.

Others are far more bullish. Alexei Miller, the chief executive of the Russian energy giant Gazprom, forecast a crude price of $250 a barrel for “the foreseeable future,” Reuters reported Tuesday from Deauville, France. That will mean sharply higher gas prices for Europe, he added.

A crude oil price below $100 a barrel, he said, would still mean that extraction from deep wells, tar sands and shale would be profitable and it would also trigger new investment.

By contrast, the energy agency said that the recent abnormally high price was largely explained by fundamentals. It agreed that the supply shortfall was in diesel, meaning more investment was urgently needed in the refining system.