Engineering firm Doosan Babcock said it was meeting employee representatives to manage the impact of the shutdown on its own operations.
Ineos claimed that the number of contractors who have been laid off at the Grangemouth complex since the dispute started last week had reached 2,000.
But local MPs said those jobs could be reinstated if the petrochemical plant reopens.
One worker said Doosan Babcock, which employs welders and pipe fitters at the site, had laid off 107 staff, but this was not confirmed.
A spokeswoman said: “Doosan Babcock has been impacted by the situation at Ineos’ Grangemouth petrochemical plant and is currently in consultation with its employee union representatives to manage that impact. Until the consultation process is complete, we are unable to comment further.”
There are an estimated 2,000 contractors employed at Grangemouth, with a total of 10,000 jobs said to rely on the plant.
Laurence Barrett, chief executive of Forth Valley Chamber of Commerce, said there was “no question” other firms would be severely impacted by goings-on at Grangemouth. “It will have a devastating effect.”
Speaking at the site, Michael Connarty, the Linlithgow and Falkirk East MP, said: “Grangemouth always has hundreds of contractors working on all of these plants, maintaining them, and the first thing they [Ineos] said was ‘we’re shutting the plants so you can go home’.
“So all these contractors were laid off immediately and that will be an immediate effect.”
He added: “At any point there can be 1,000 on this site so probably hundreds have already gone down the road.”
However, he stressed the situation would be reversed if the petrochemical plant were to reopen, and said there was still work on the KG Flex, a project aimed at ensuring more gases from the North Sea are extracted and fully utilised.
He said: “It can be reversed though, of course, they are still working on the flexing of the KG.
“But a lot of things would go round here if this was a refinery-driven plant only, we could lose 300 contractor jobs overnight.”
Joan Paterson, deputy leader of Falkirk Council, added: “There’s so much that depends on the plant, from hotels and guest houses where the subcontractors stay, to the bakers where they buy their lunch and pubs where they go in the evening.
“Everything just dropped when we heard. We’ve been brought up in the shadows of the cooling towers, and we just hope the flares will be lit up again.”