Biba has said consumers are unaware of the dangers of buying insurance from non-regulated companies.
The industry body said the secondary insurance market was a particular concern.
It warned consumers that buying insurance from non-regulated companies could be risky.
Purchasing insurance from a company with interim permission, it warned, could also have dangers.
Biba chief executive Eric Galbraith said: "We are concerned about those companies who have temporary authorisation, particularly because the consumer does not have access to the FOS or FSCS until the firm is fully authorised.”