The United States has so far escaped the crippling fuel protests that have swept across Europe.

But with petrol prices in some parts of the US having hit a record high this summer, and wholesale diesel costs rising steadily, truckers say they have not ruled out direct action.

"Protests and boycotts are not out of the question," said Sandy Soendker, an official with the Owner Operator Independent Drivers Association in a Reuters interview.

Compounding popular discontent with the cost of fuel, the price of heating oil is expected to surge by up to 50% this winter.

Americans use more oil per capita than any other country - about twice the European average.

Although fuel blockades have not yet hit the US, their impact would be felt that much more sharply if they did.

Gore does not want protests over fuel during his election campaign

US President Bill Clinton said earlier this week that Washington was closely monitoring crude oil prices, and was considering emergency options to tackle high fuel costs.

"We need to make sure we do everything we can to get through this winter," he said.

The price of oil has been raised as an election issue.

George W Bush blamed higher oil prices on the White House, which he says failed to expand domestic exploration and imposed too many regulations.

Volatile oil prices last winter meant that some homeowners in the north-east - where there are heavy winter snow falls - saw their heating bills more than double.

Low taxes

However, Americans still have the lowest petrol prices in the world. A litre of petrol in the US costs just $0.46, whereas in the UK it costs $1.14.

And of this price, only 22% is tax in the US, compared to 73% in the UK, 71% in France, and 69% in Germany.

The price of petrol has fallen by 18% since its peak in June, going some way to ease the fears of motorists.

The White House also has the option of falling back on the nation's vast emergency stockpile of oil.

The reserve, which was created by Congress during the oil crisis of the 1970s, holds 571 million barrels of crude in underground caverns in Texas and Louisiana.

It is the largest emergency supply of oil in the world.

A bill is also being discussed in Congress that calls for fuel surcharges on shipping costs every time the price of diesel suddenly rises by 5 cents a gallon.

Clinton's warning to Opec

President Clinton said that the fuel crisis was being triggered by the failure of the main oil producing cartel, Opec, to keep up with demand in the West.

He said the fundamental problem was that strong economies in Europe and the United States had boosted demand for oil, and Opec had failed to keep up with soaring consumption.

When Mr Clinton met Crown Prince Abdullah of Saudi Arabia at the UN summit, he warned that the world was at risk of plunging into recession unless something was done.