Alexander Dennis workers go on strike over pay
Six hundred workers have gone on strike at the Alexander Dennis bus factory in Falkirk - the first of two stoppages.
The Unite union has rejected a 3.5% pay offer - saying it was below expectations at a time when profits and executive pay were rising rapidly.
The company said the offer was more than fair and has urged staff to call off the strikes.
Bosses earlier suggested they may have to move production away from the Camelon base as a result of the action.
The strike was called after pay talks with Acas broke down.
But on Wednesday the firm warned it would "have a clear impact" on its future strategy.
A senior ADL figure added the company would "have to look seriously at where we build vehicles in the future".
Unite has been pressing for a 4% pay rise but the company has offered 3.5%.
Unite official Lyn Turner told BBC Radio's Good Morning Scotland programme: "I'm urging the company to get back round the table to continue discussions.
"The last thing that anybody wants is to take industrial action. But we felt it necessary because the company wasn't listening anymore."
The union said about 600 of the 800 staff based at the ADL factory would take part in the action.
The first 48-hour strike began at 06:00 on Thursday and will end just before 06:00 on Saturday. A second strike is due to get under way at 05:54 on Sunday and end at 05:54 on Tuesday.
An indefinite overtime ban is already in place.
The Falkirk-based firm, which employs about 2,400 staff in the UK and abroad, reported a 56% rise in pre-tax profits to £24.2m in July.
A senior company official, who did not want to be named, said: "We have offered a very fair deal. Effectively it represents a 15% rise on a compound basis over four years.
"There is no other UK manufacturing company, to my knowledge, that has offered a wage anywhere near that.
"An average bus vehicle builder at the company earns £32,000-plus a year.
"Obviously this (action) will have a clear impact on our forward strategy and we will have to look seriously at where we build vehicles in the future."