Up to 150 Tesco lorry drivers have begun a strike after refusing to sign up to new working terms and conditions.
Drivers at the Livingston depot will strike for three days
The dispute came after the supermarket chain revealed plans to move its depot in Livingston, West Lothian, to a new site nearby.
Local MP Jim Devine has called for a one-day boycott of Tesco for threatening to sack drivers who refuse to sign the new contract.
A Tesco spokesman said the chain "strongly refuted" Mr Devine's claims.
The drivers, all members of the Transport and General Workers Union (T&G), are taking part in a strike which is due to last from Thursday until Saturday.
Tesco vehicles were having to turn around at the warehouse as workers formed a picket line, according to union members.
The T&G claims the new contracts, brought in with the move to the new site, mean losses to the drivers of between £3,000 and £6,000 and the de-recognition of the union.
Tesco strongly refuted claims that the drivers would lose any earnings under the new conditions.
The T&G, now part of the Unite union, said drivers voted by 126 to six to strike.
Ron Webb, the T&G's national transport secretary, said: "We said we'd fight back against the way our members were being treated and that fight has begun.
"We are determined to expose this company for the arrogant way it has treated its staff, our members, and the union itself."
He said Tesco had stepped up security in the area.
Mr Devine, the MP for Livingston, said: "It is my opinion that Tesco is behaving in a truly draconian fashion which puts one in mind of the behaviour of 19th Century pit-owners."
He added: "I am asking people to consider the position of these drivers, search their conscience and consider a boycott of all Tesco outlets this Friday."
Mr Devine and Falkirk East MP Michael Connarty have written to Tesco demanding an urgent meeting with management.
A Tesco spokesman rejected Mr Devine's allegations. He said no drivers were losing their jobs and that new jobs were being created.
Laurie McIlwee, distribution director for Tesco, said 450 of the 600 workers moving from the existing Livingston warehouse to the new one had signed up to the new terms and conditions.
Speaking on BBC Scotland's Good Morning Scotland programme, he said: "There are none of our existing drivers who, when they move from the old contract to the new contract, will have any change in contractual pay.
"We absolutely guarantee that for the lifetime that they work at Tesco."
Mr McIlwee said there had been a lot of miscommunication over the new conditions.