Wakefield-based Mid Yorkshire Hospitals Trust is under growing pressure to scrap the planned transfer of 900 staff into a private company.
Under the cost-saving scheme cleaners, IT specialists and maintenance workers could be moved into an outside company set up by the trust, which runs Pinderfields, Pontefract and Dewsbury hospitals.
While the wages and holiday entitlements of current staff would be protected, newly-recruited workers could be employed on different terms and conditions.
Mid Yorkshire is awaiting a decision from the health regulator NHS Improvement on whether it can go ahead with the scheme.
In the meantime, public sector union Unison is poised to call its members out on strike if Mid Yorkshire does not ditch the plan.
And now four MPs have told trust bosses to drop the proposal after they saw a report which sets out how the company would operate.
Labour’s Yvette Cooper, Mary Creagh, Paula Sherriff and Tracy Brabin said the plans involved saving £1m a year on staff costs.
They also warned that current staff who transfer to the company could lose pension benefits.
Ms Cooper, the MP for Normanton, Pontefract and Castleford, said: “Mid Yorkshire’s own papers show their plans depend on using the NHS for private patients and cutting sick leave, holiday leave, and pensions for new staff. That’s unfair and goes against the principles and values of our NHS.”
The staff transfer is being proposed after Mid Yorkshire ended the last financial year with a £20m deficit.
Dewsbury MP Paula Sherriff said: “Mid Yorkshire face unprecedented financial pressures but the answer is not a plan that amounts to the backdoor privatisation of our NHS.”
The MPs said Mid Yorkshire was pressing ahead with the plan despite neighbouring Leeds Teaching Hospitals NHS Trust putting a similar proposal on hold.
The Leeds trust said it would not go ahead with the transfer of more than 2,000 staff this financial year.
Elsewhere, health unions at York Teaching Hospital have threatened strike action as talks over staff transfer plans are held.
Wakefield MP Mary Creagh said: “Other areas have forced similar plans to be abandoned. It is time for people to speak out against these plans and for Mid Yorkshire to stop this backward step.”
Batley and Spen MP Tracy Brabin said Mid Yorkshire staff did not want to lose their NHS status. She said: “We cannot have a two-tier workforce where two people in the same job, working side by side, have different terms and conditions of employment.