Two major trade unions have denounced Nestle's plans to close its career average defined benefit (DB) scheme as a "betrayal" of staff.
Unite and GMB said over 7,600 Nestle workers in the UK would be affected by the closure and criticised the firm for going back on pension promises it made in 2010.
Five years ago the final salary scheme was replaced with a career average arrangement and a money purchase scheme was also introduced for new joiners.
Unite said its members had agreed to these changes "in good faith on the understanding that their pension would be secure for the future".
But if the proposals go ahead the career average scheme will be closed to new entrants from 2016 and closed to future pension build up for existing members from the start of 2017.
Now Nestle plans to close the career average scheme due to increasing costs and liabilities.
Firms have come under increased scrutiny for the way they consult over scheme closures, after a judge ordered IBM to pay damages to workers who lost out after it closed its DB scheme.
Unite head of media and campaigns Alex Flynn told PP: "For many people this the thin end of the wedge. At the end of the day people have made plans based on their retirement plans, plans for the future on the understanding that they would have a particular pension which would deliver an income.
"So there people are unhappy about it. We will be looking to engage with the company and get more detail about what they are planning. But we will be arguing that the present scheme remains as it is."
Unite has 2,000 members who work for Nestle.
GMB national officer Stuart Fegan added: "We urge Nestle to think again on these proposals as we fear that the UK workforce will not accept these changes willingly.
"Strike action with all its consequences for Nestle's corporate brand if these proposals are implemented, looms large across Nestle in the UK at present."
In a statement, Nestle UK and Ireland chairman and chief executive Fiona Kendrick said: "We realise that these proposed changes will cause concern for employees who are building up defined pension benefits in the Nestle UK Pension Fund, or are eligible to do so. We are very sorry that we have to propose these changes but under the circumstances we believe it is the right option."
Nearly every trustee is confident of the next stage in their scheme’s strategy, despite almost an equal number being forced to consider replacing plans within the prior 12 months, according to research by Barnett Waddingham.
Companies could be overstating their pension liabilities by up to £60bn due to their life expectancy assumptions, according to XPS Pensions Group.
Defined benefit (DB) schemes that provide GMPs must revisit and, where necessary, top-up historic cash equivalent transfer values (CETVs) that have been calculated on an unequal basis, a landmark court judgment said last week.
Regulators must act now to impose some "proper regulation" to stop another defined benefit (DB) transfer advice disaster, saysTim Sargisson.
Opportunities for defined benefit (DB) schemes to pursue investment approaches that help repair the UK’s economy cannot stand in the way of improving member outcomes, Aegon says.