A bitter row broke out between the Pension Protection Fund, the pensions lifeboat, and some of Britain's leading consultancies yesterday over a revised formula governing the amount employers pay into risk-based levy schemes.

A change to the so-called "scaling factor" means many pension schemes will be paying 2½ times as much as they originally anticipated, Aon Consulting claimed.

The move "adds further misery to pension scheme finances", the consultancy said as fellow consulting group Watson Wyatt said the change meant that employers who had put more money into their pension scheme in the belief that would lower the amount of levy they pay are "running to stand still".

Jeremy Dell, a partner at pension lawyers Lane, Clark and Peacock, accused the fund of "sheer incompetence" in failing to forecast the way the formula would change "with any degree of accuracy".

The PPF raises a levy on pension schemes as a form of insurance, so that if schemes go under members will have the bulk of their pension rights protected.

Partha Dasgupta, its chief executive, said the lawyers and consultancies were being "highly misleading" and "scaremongering" in predicting huge levy increases.

The change, he said, would ensure merely that the PPF brought in the £675m it said it needed for this year and the two next.

Scheme funding had improved recently, Mr Dasgupta said. "But it is the long-term risk that we have to protect ourselves against, particularly as we are in the middle of a credit crunch, which can only mean a lot more uncertainty".

The change brought in no more money than originally planned, he said. What it did do, is alter who pays what so that the schemes with riskiest long-term profiles pay more.

"It is not good news for all schemes, and some where the risk is larger will pay significantly more," Mr Dasgupta said. "But that has to be right, because the burden should shift from those schemes that are doing a good job in sorting out their finances to those that have not. I take great offence at the way people are trying to portray this [change]."

Under the formula, he said, 42 per cent of schemes would pay a lower cash sum this year than last while 57 per cent would pay a higher cash sum. But as a percentage of assets, 58 per cent of schemes would be paying a lower percentage.

Mr Dasgupta said 9 per cent would pay no risk-based levy at all this year, because they had taken steps to fully fund their pension scheme. "That is fair. It redistributes the risk fairly within the population of schemes."

He also added that the consultancies "need to keep a sense of proportion". Almost half of the 14 per cent of schemes whose levy will more than double, paid only £5,000 or less to the PPF last year.

But John Ball of Watson Wyatt said that those who had taken steps to improve their solvency with the aim of reducing their levy would still now find "that the PPF has moved the goalposts and they will have to pay more than they thought.

"Pension schemes have become the latest victim of the credit crunch, with the PPF suggesting it needs to build up a war chest before things get worse."