Rachel Reeves has been urged to rule out another tax raid on retirement pots after the appointment of a pensions minister who has called for sweeping reform.

Following the promotion of Torsten Bell to the job, industry experts want guarantees from the Chancellor that pension savings will not be targeted as she looks to plug a hole in the nation's finances.

Bell, the former head of the Left-wing Resolution Foundation, has in the past made the case for 'completely reforming' pensions tax relief in a move that would hit millions of Middle-Class workers.

He has also advocated a sharp cut in the amount people can take out of their retirement pots tax-free from £268,275 to just £40,000.

Bell is a former adviser to Ed Miliband and best-known for masterminding the disastrous 'Ed Stone' stunt, which saw the then Labour leader commission a slab of limestone with his pledges carved into it.

His appointment as pensions minister has sparked speculation that Reeves could hit pensions once again in a 'mini-Budget' in March having dragged them into inheritance tax for the first time in the Budget in October. 

It is feared that talk of cutting the tax-free lump sum would be particularly damaging as savers rush to withdraw cash from their pension pots – as they did before the last Budget. Experts have warned that this will leave many worse off in retirement.

Helen Morrissey, head of retirement analysis at Hargreaves Lansdown, said: 'We've seen the damage that speculation can do with people rushing to take their tax-free cash ahead of the recent Budget only to find no changes were made. It's not a situation anyone wants to see repeated.

'People need the certainty to plan for the future without worrying about their efforts being undone by changes further down the line.'

Pensions and savings investment platform AJ Bell called for the Chancellor to agree a 'Pensions Tax Lock' to take any changes 'off the table for the remainder of this Parliament'.

Rachel Vahey, head of public policy at AJ Bell, said: 'The Chancellor should nip the spectre of damaging rumour and speculation in the bud.'

The Treasury, however, has refused to rule out another tax raid on pensions.

Former pensions minister Baroness Altmann this week told the Mail that 'private and state pensions are under attack'.