Hundreds of lorries were expected to cause major disruption to city centre traffic today with a demonstration against high fuel prices.

Police expected between 350 and 400 trucks to join a go-slow cavalcade through the centre of Edinburgh.

A similar protest took place in Cardiff earlier this month but other protests around Britain were called off after the Government agreed to look again at its promised fuel tax rise.

Prime Minister Tony Blair said a decision would be taken later this year on whether to press ahead with the 1.9p-a-litre fuel tax hike in September.

The Road Haulage Association (RHA) demonstration in Edinburgh was due to start outside the city centre in the seaside suburb of Portobello.

Vehicles were expected to gather in Sir Harry Lauder Road from 7am and move off at 10am.

The convoy was going north of Holyrood Park along London Road, down Princes Street and past Haymarket station before heading west and finishing at Gogar Roundabout.

Hauliers are angry at the high cost of fuel, which is fluctuating at around 80p a litre.

They claim this is damaging road freight businesses and warn that many firms will go bust if Chancellor Gordon Brown imposes the tax rise on September 1 as planned.

The latest demonstrations bring to mind the wave of fuel protests which swept across Britain in September 2000 and all but brought the country to a halt.

Phil Flanders, the RHA director for Scotland and Northern Ireland, said his members were "suffering like never before".

"Operators are now working to the tightest possible margins. Making even a small profit on a job will soon be a thing of the past," he said.

Meanwhile, Greenpeace is set to join the convoy - in a bid to highlight the dangers posed by global warming.

Environmentalists will drive vans in the convoy emblazoned with the slogan "Global warming kills - Keep the fuel tax".

Greenpeace climate campaigner Rob Gueterbock said: "These lorry drivers are wrong to call for the Government to cut the tax.

"Global warming is the biggest threat to mankind and is already killing tens of thousands of people every year and devastating the lives of millions of others.

"The financial cost will run into billions.

"We need fuel taxes as a vital part of the fight against global warming."

A Lothian and Borders Police spokesman said: "We have had regular meetings with the demonstration organisers to plan the route and try to minimise disruption to traffic in the city.

"However, we expect there will be delays for anyone planning to come into Edinburgh. We would advise the public to be aware of which roads are being used and seek an alternative route.

"We hope the demonstration will be over by around midday and traffic should start getting back to normal levels then."

The Chancellor has said he will review the tax hike in August but he wants to focus on persuading Opec, the oil exporters' cartel, to bring down international prices.

Opec members agreed earlier this month to increase production by 2 million barrels a day in an effort to cool the price of crude.

Scotland's First Minister, Jack McConnell, told the Scottish Parliament on June 3 that Mr Brown should look again at the fuel duty increase if international pressure fails to bring down the price.

And Tory leader Michael Howard faced a volley of criticism after he openly supported the fuel protesters in a television interview.