Scottish Labour leader Johann Lamont has urged Grangemouth oil refinery owners to return to the negotiation table with their workers instead of behaving in a "Dickensian" way that "cannot be tolerated."
Mr Lamont said the closure was a "hammer blow" to the whole of the UK and criticised Ineos for "threatening" their staff.
"It cannot be right in 21st century Scotland that an employer demands that a worker accepts cuts to their wages, their pensions and their conditions, and are told to either agree to them within 96 hours or face the sack.
"That is a Dickensian way for an employer to behave and cannot be tolerated.
"There is a committed workforce at Grangemouth. If the Ineos management is equally committed to their business they will negotiate with their workers, not threaten them."
Grangemouth owners Ineos are in last ditch talks with the workers' union, but the workforce is just one of the problems facing the plant.
Thousands of jobs are under threat after a dispute over conditions led to a shock decision to close the petrochemical site in Grangemouth.