The rethink comes after reforms in the USA in the wake of corporate scandals such as Enron, where huge debts were hidden to deceive investors about the firm's true trading position. Some British PFI contractors have also been accused of disguising their financial liabilities.
Under present regulations, contractors do not list debt incurred in course of PFI projects on their balance sheets but instead assign it to the special purpose vehicle, or SPV, created to build the project.
They are allowed to do this because, usually, shares in the project are divided equally between the partners in the PFI consortium, and none is responsible for the debt left if a contract collapses.
Changes to accounting rules in the USA have put an end to this practice. They stipulate that a partner can be deemed to have a "controlling interest" in an SPV or joint venture, even if it has an equal shareholding. It is therefore obliged to show its assets and liabilities in the accounts of the parent company rather than just in the SPV.
The new US regulation lists ways in which a company can be deemed to have a controlling interest in a consortium, even if it has an equal stake. One of these is the power of veto over decisions.
The International Accounting Standards Board has called on its financial reporting interpretations committee to investigate whether it ought to adopt the US model. If the committee concludes that it is better than existing regulations, the UK would be obliged to follow suit.
Paul Ebling, project director at Accounting Standards Board UK, said: "If the IASB issues something that follows the US model then the UK would have to adopt it by 2005."
The effect of this would be that if a contractor was deemed to have some kind of controlling interest in a special purpose vehicle set up to finance the PFI project, it would have to show its assets and liabilities on the balance sheet.
Contractors complain that this would give an unfair impression of the company's exposure to bank debt and affect its attractiveness to the market. This is because, controlling interest or not, the company is not ultimately liable for the debts of an SPV. (Debt is paid by the fund lender, usually a bank.)
Laing has about £550m worth of debt in PFI-related special purpose vehicles. Laing finance director Adrian Ewer said: "This is a separate issue from a company's bank debt. Any attempt to put this on to group debt would just be misleading."