That’s according to financial services consultants Punter Southall.

Some forecasters believe the Treasury is considering further cuts to the annual allowance, which has already been reduced from £255,000 to £50,000, in a bid to save money.

Last December, the government published an estimate that a cut in this limit to £40,000 would save the Treasury £600m a year.

Others have suggested it may be cut to as little as £30,000.

But Punter Southall is urging George Osborne to leave the existing tax relief in place.

Mike Richardson, the group’s head of pensions taxation, said: “Faith in pensions as a form of saving for retirement is at an all-time low and making further changes to pensions tax relief now risks completely destroying any last remnants of that faith.

“The regime is already horrendously complicated, and any further alterations to pensions tax relief would be counterproductive and damaging to long-term pension savings.”

Richardson said new changes could appear “oddly disjointed” from other government policy, particularly considering the recent first-phase roll-out of auto-enrolment.

“Auto-enrolment will only be a success if employees believe that they can safely plan for their retirement using a pension, but that simply won’t happen if the government keeps changing the rules,” he said.