It said the existing scheme caps maximum cover at £1m, making it suitable only for SMEs, and, as a result, it has failed to attract significant take-up.
The perception is that the scheme is only applicable to credit-insured clients, such as paper merchants, that have had their credit insured limits reduced, according to Aon.
Additionally, if a credit limit has been removed completely, the top-up scheme cannot help as it has nothing to top-up.
James Bowker, Aon account director, said: "Because credit insurers are sustaining high levels of claims, they are focused on managing their risk exposure levels and the paper sector, among others, is seeing a high volume of credit limit cancellations ongoing."
Aon is pushing for the scheme's scope to be broadened so that it is similar to the French system, which covers withdrawals as well as reductions in credit.