A leading consultancy firm is warning companies they may be paying too much into their pension schemes, and advising them to renegotiate agreements made with trustees.

Hymans Robertson said yesterday that favourable market conditions have reflated many schemes since agreements were made, and "companies paying more than necessary on pension deficits are in serious danger of harming their bottom line".

A string of blue-chip companies has agreed funding schedules with their trustees this year, in closely-watched deals such as private equity giant KKR's negotiation with Boots. Other potential deals, such as the initial private equity bid for Sainsbury and the recent approach for Scottish food group Devro, foundered on pension negotiations.

However, finance directors should now "revisit deficit funding agreements put in place with their pension scheme trustees in 2006 or early 2007 in light of improved performance experienced by many funds", according to Hymans Robertson.

Martin Potter, partner at the firm, said: "FDs who committed to high pension contributions last year could find themselves paying more simply because their pension schemes valuation came at a time when financial conditions were unfavourable.

"If the same FDs were negotiating their pension contributions now, the outcome would most likely be much lower contributions."

Pension fund deficits among the top 200 companies fell in April to £3bn, their lowest level since the FRS17 standard was introduced six years ago, according to rival Aon Consulting, which estimated almost half of the funds to be in surplus by the end of May. However, it also warned that FRS17 surpluses would need to top £100bn before pension promises could be fully secured with insurance companies.

Potter added: "This is real money, and once paid into a pension scheme the prospect of ever getting it back is negligible. Improved funding positions are also a great platform for taking some investment risk off the table and cashing in some of their chips'."