An estimated £45m in premium payments has been lost according to one creditors' group, however, it is not known what the damage will be to firms with outstanding claims.
An insurance source said: "If the claims hadn't been paid out when Independent Insurance collapsed – even if they had been agreed – then firms will miss out on their money.
"This means they will have to find the money to pay for it themselves, which will hurt because it won't have been budgeted for. We're looking at potentially hundreds of millions for total losses."
Although private policy holders are protected by the Policy Holders Protection Board, commercial policy holders do not enjoy the same cover, and may have to go to court to recover compensation.
The losses have spurred the construction industry into action. Some creditors have formed the Creditors of Independent Insurance Action Group, which will lead any legal action and lobby for government intervention. The Construction Confederation was also finalising its battle plan this week.
Sources admit that they are uncertain how much money will be recouped, with some describing the chances of success as "very low".
Some small and medium-sized firms may face ruin, and large contractors such as Carillion, Mansell and Balfour Beatty have been hit.
The CIIG said it was leading plans to sue Independent's auditors, KPMG, the DTI and the Financial Services Authority. An investigation into who will be sued is under way.
Rob Green, the CIIG's spokesman, said the DTI and FSA were supposed to protect Independent's customers.
He said: "They are supposed to regulate the industry but in this case they appear to have failed to identify that there was a problem; KPMG audited the books, which was the basis of policy holders' confidence in Independent Insurance."
CIIG chairman Kevin Young, managing director of construction insurance broker Argyll, was to meet Brent North MP Barry Gardner yesterday to discuss political action. Stephen Alexander, of law firm Class Action, will handle any lawsuit.
