Royal Mail plans to close its final-salary pension scheme to all employees in a move that could plunge the business further into industrial turmoil.

The decision is expected to trigger strikes by thousands of postal managers, in addition to unrest among its 130,000 employees who are in dispute over pay and working arrangements.

Royal Mail is expected to write to employees soon to outline sweeping changes to the pension scheme, including raising the retirement age by five years.

Its move to close the final-salary scheme for existing employees, along with new ones, is almost unprecedented. Rentokil is one of the few other large organisations to take such drastic action. Usually companies that change pension schemes pull down the shutters on final-salary arrangements to new employees only.

The move to end the scheme comes days after Royal Mail denied that it had any such plans. Nevertheless, the proposals are believed to have been outlined to senior managers two weeks ago. The organisation will begin a two-month consultation on the plan soon.

In another controversial move, Royal Mail is to propose “banking” current benefits and linking them with RPI rather than salary levels. Unite, which represents 12,000 post managers, says that this change would cost pension scheme members £1.5 billion.

Paul Reuter, national officer for the union, said: “Even accounting for inflation, the £1.5 billion that the members could lose far exceeds the amount taken from Royal Mail by the great train robbers.

“We call upon Royal Mail to honour their commitment to preserve the past service benefits that have been built up and paid for by our members. We also call upon Adam Crozier [the chief executive] to honour his commitment given in February to safeguard final-salary schemes going forward. Failure by Royal Mail to respond positively will leave Unite with no option other than to ballot its members for strike action.”

Royal Mail is facing a wave of national strike action from the Communication Workers Union (CWU) in one of its most turbulent periods of industrial relations for many years. More than 130,000 CWU members are threatening to stage two 48-hour walkouts either side of a Monday next month, triggering five days of disruption because very little work is now done on Sundays. Unless Royal Mail backs down on the pension changes and improves a pay offer, the two national walkouts will be followed by continuous selective action across all operations in the postal network.

Unite is due to meet Royal Mail today, but it does not believe that the pension proposals will be changed. It is understood that the postal group will say that it wants to drop the final-salary scheme in favour of pensions calculated on career average earnings indexed to RPI and capped at 5 per cent from April next year.

In February Royal Mail announced the closure of the final-salary pension scheme to new employees. Then Mr Crozier said: “It is important we safeguard the future of the pension fund for our people, who regard a final-salary pension scheme as a key benefit of working for Royal Mail.”

The retirement age is to be lifted from 60, which is enjoyed by many public sector workers, to 65.

A spokesman for Royal Mail said that he could not comment on proposals before employees are informed.

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