Co-operative Insurance (CIS) says its rival insurers must open themselves to public scrutiny if they want to build consumer trust.
The insurer made the call on the back of its new Social Report that shows a massive public mistrust of insurers.
CIS general manager, Martin Clarke, said: "Customers will only start to regain faith when insurers are fully open and transparent about what they do and why they do it.
"If insurance companies are brave enough to have a proper social programme, as we have over the last year, then they can go a long way to restoring people's confidence."
While CIS's report centred on the activities of the financial services industry, general insurance was also heavily featured.
A spokesman for the insurer said: "There is clearly under provision of home insurance and we have got to ask ourselves why is that?
"It is not just because of financial exclusion it's because of miss-trust between consumers and insurers."
Last year CIS managed to retain 93% of its motor insurance customers and 95% of its household customers.
The insurer received £191m in premium income from motor while paying out £130m in claims.
It paid £90m in household claims while receiving premium income of £165.9m.