The situation is not critical, it's not likely to become critical

Ray Holloway, Petrol Retailers' Association

But retailers have sought to calm the situation amid reports of panic buying, saying a fuel crisis is unlikely.

The biggest protest has been at Milford Haven, Pembrokeshire, where two oil refineries run by Texaco and Elf have been blocked by around 50 lorries since Friday.

Workers on Saturday morning were forced to enter the depot on foot as protesters including members of the public, farmers, taxi drivers and coach operators blocked road access.

Shell Oil's Stanlow refinery at Ellesmere Port, in Cheshire, and a petrol distribution depot at Avonmouth near Bristol are also being targeted.

Shell warned that 20 to 30 stations in the North West would run out of petrol "imminently" as a result of the Stanlow protests, while Sainsbury's said two of its 223 petrol stations had already run out of fuel.

Tesco in Bidston Moss on the Wirral reported it had run out of petrol, while cars queueing for petrol at a Tesco in Allerton were causing traffic problems.

'Businesses will suffer'

But Ray Holloway, director of the Petrol Retailers' Association, said that 30 or so filling stations out of 1,200 did not mean Britain was running out of petrol.

He told BBC News Online that companies were coping with the situation by using supplies from other refineries.

"The situation is not critical, it's not likely to become critical," he said.

A go-slow by lorry drivers caused chaos on Tyneside

"Remember, most of the transport industry protestors are owner-drivers and their businesses will suffer if they don't go back to work next week.

Milford Haven protester Mike Greene, who runs a family haulage business in Llanelli, west Wales, said: "We will have to wait and see what happens before we decide how long we are going to stay here.

"We may not be stopping many tankers coming in or out but we are still making our presence felt and getting our message across."

Panic-buying

Panic-buying has seen some Sainsbury's petrol forecourts selling up to 30% more fuel in the last few days, a spokesman said.

BP had warned that one in seven of its 140 petrol stations in the North West were running short but later said most had been restocked with only a "handful" left empty.

Managers at Texaco's Milford Haven refinery are said to be unconcerned by the blockade as most of the seven million gallon daily fuel output is pumped out by pipeline.

In France, the main truckers' and farmers' unions have called on their members to call off the dispute.

The government in Paris, which offered to cut diesel tax earlier this week, has refused to offer any more concessions to the protesters.

Right to protest

Meanwhile, Deputy Prime Minister John Prescott has been visiting Liverpool, close to Ellesmere Port, for two engagements despite earlier reports he had cancelled to avoid fuel price protests.

Aides denied the claim and said the cancellations were down to "extra Government commitments".

Tankers were prevented from leaving the Stanlow refinery in Cheshire

Shadow Transport Secretary, Archie Norman, has defended the right to peaceful protest against high fuel prices.

Mr Norman said demonstrators, while he sympathised with them, should direct their protests at the government.

He told BBC Radio 4's Today programme: "I cannot condone direct action. I feel the person to be protesting at is Gordon Brown and the government, not the oil refinery."

The protests could be spreading to Ireland next week after the Irish Road Haulage Association, which represents 1,200 of Ireland's 4,000 truckers, announced protests on Friday and the following Monday in support of its claim for a reduction in fuel duty.