Employers should be able to go back on pension promises made to staff, according to leading UK pensions expert, who has claimed that there should be a "one off opportunity for employers to renegotiate the past."

Alan Pickering is on the board of the Pensions Regulator, a body set up by the government in 2005 to ensure that company pension schemes are sufficiently funded. His comments were made at the National Association of Pension Funds conference in Edinburgh, and reported by the Financial Times.

Last week Mr Pickering, who authored a report on pensions for the government in 2002, criticized the Turner report. The report calls for a National Pensions Savings Scheme which Mr Pickering said would cause lethal damage to existing funds.

Amicus, the trade union, said it would fight any attempt to cut pensions. It said: How can you even think of depriving people of the hard-earned money they have put away for their retirement?