The Unite trade union has hit out at proposals by the UK's biggest bus builder Alexander Dennis (ADL) to cut 260 jobs from its Falkirk base.
The union said they had already agreed to work a four-day week with workers being asked to shoulder more wage cuts.
ADL announced on Thursday that it had entered a 90-day consultation with the union on the future of the jobs after a 50% drop in its core market.
They said if staff were unprepared to work shorter weeks, the jobs would go.
Scott Foley, Unite's regional industrial organiser, said staff had been on a four-day week since September in order to preserve jobs and that the agreement would remain in place until March 2010.
Both sides have also agreed to move holiday leave from September to January 2010 and to extend Christmas and New Year breaks.
The union questioned why further cuts were needed when it was anticipated that market conditions in the sector would improve "soon".
Mr Foley said: "Our members fully understand the difficult trading conditions the company faces in the short term.
"However, our members also believe that any financial hit should apply equally to all workers at the site, including the senior management team."
He said that workers were being asked to lose a further £43 from their weekly wage packets and that the cuts would be "very hard for workers to endure".
ADL, which employs about 900 workers at the site, has blamed a 50% decline in demand for new vehicles.
A spokesman for the firm said formal talks had been ongoing with trade unions to reach agreement on the issue.
Both side are due to meet to discuss the current situation on Tuesday 17 November.