The FSA has issued a warning for consumers holding policies from CIC Insurance Company SA or CIC Insurance Company AVV. It said policyholders may not have effective or enforceable insurance cover.
It said, in the case of EL cover, this could put firms in breach of the Employers' Liability (Compulsory Insurance) Act 1969.
The FSA said it was currently aware of around 2200 policyholders who may be affected, involving an estimated £3.75m in premium.
It said policyholders were strongly advised to make alternative arrangements with an authorised insurer, and called the issue a matter of urgency.
The news comes only a month after the FSA warned that 40,000 Tribune Risk and Insurance Services policyholders were without cover.
It said the two companies had been carrying out insurance business in the UK, through UK underwriting agents, without authorisation.
According to the FSA, CIC Insurance Company SA claims to be based in Greece, although the Greek authorities said it had no authorisation to carry on insurance business there. It also has no permission to operate in the UK from Greece and so has no authorisation within the UK.
The FSA has been told that CIC Insurance Company SA is not incorporated in Greece, and so does not officially exist, and any insurance policies held with the company are void.
"Any policyholders who believe themselves to be insured with CIC Insurance Company SA would not be insured for the risks the insurance policy says that it covers," said the FSA.
In a similar situation, CIC Insurance Company AVV claims to be incorporated in Aruba, said the FSA. It was currently unclear whether this was the case or not, although the company was not authorised to conduct insurance business within the UK.
The FSA said: "If CIC Insurance Company AVV, is not incorporated, the position is the same as with CIC Insurance Company SA.
"If it is incorporated, any policies with it may be enforceable in civil proceedings at the instigation of the policyholder. Policyholders may wish to seek professional advice on this."
The FSA warned CIC policyholders that they would not be eligible to claim compensation through the Financial Service Compensation Scheme, as the two companies were operating without authorisation.
