A four-day strike over pay by hundreds of Shell fuel tanker drivers began on Friday morning after last-ditch talks broke down.
The drivers say they have not had a pay rise since 1992 while the Anglo-Dutch oil giant is making profits of 1.3 billion pounds a month.
But Shell said it was not party to talks on Thursday which were between the union and haulage firms contracted to deliver fuel to Shell garages across the country.
The two haulage firms involved say they had offered pay rises of 7.3 percent backdated to January and another six percent from January 2009 and asked Unite to put the offer to a ballot of its members.
They said the double pay rise would take a driver's annual pay to 41,500 pounds.
They said this offer had been rejected.
Unite said the dispute could have been resolved if Shell had stepped in rather than sitting on the sidelines.
"One of the world's richest companies is prepared to play Pontius Pilate and see the British public inconvenienced rather than settle this dispute for a sum smaller than the chairman's pay increase last year," said Unite assistant general secretary Len McCluskey.
The strike is likely to affect deliveries to one in 10 of the country's 9,500 garages. Drivers in some parts of the country were reported to already be starting to stockpile fuel.
Prime Minister Gordon Brown had appealed on Thursday for the strike not to go ahead.
It comes amid protests by road users at the rocketing price of road fuel as crude oil has jumped to over $130 a barrel.
