LONDON -- Oil at $100 a barrel? That may not be the worst of it.

Several leading oil experts, gathered here yesterday for an annual energy conference, sketched a near-term future in which mounting global demand and shrinking supplies push oil prices well past the $100-a-barrel (U.S.) mark.

Consuming countries, they argued, will simply have to deal with the fact that new pockets of oil are getting far harder and more expense to tap. That, combined with years of underinvestment by the industry, has led to a tapering off of new oil supplies that will continue for years, despite rising energy demand in Asia, the Middle East and some industrialized countries.

Yet on a day when U.S. benchmark oil prices retreated from Monday's record high, closing down $3.15 a barrel, or 3.4 per cent, to $90.38 on the New York Mercantile Exchange, two OPEC ministers at the same gathering insisted that the immediate problem is not too little oil.

Prices have jumped nearly 40 per cent since early this summer, the oil ministers of Qatar and the United Arab Emirates said, because of the slumping dollar, widespread Wall Street speculation and bottlenecks in the refining process.

"Please don't blame us" for record oil prices, said Abdullah al-Attiyah, Qatar's minister of oil, expressing a sentiment that is widely held among major oil-producing countries. "You have blamed us for 50 years."

The debate over what is driving the current surge in oil prices is sure to get more spirited if prices continue to soar and oil executives, consumers and politicians seek to assign blame. But the feuding theories at this year's Oil & Money conference also show how hard it is to pinpoint a cause.