UP to one in five people are submitting false information when taking out insurance policies, brokers claim.
This is far higher than previously thought, but strict data protection rules mean insurers can't cross-check information they get from consumers at the policy quote stage, the Irish Brokers Association (IBA) said.
The brokers' body said people were making false declarations on motor and home insurance application forms.
But this was not discovered until there was a claim and all the details submitted by the consumer were examined.
Failing to disclose previous claims, penalty points or convictions mean people can get lower motor premiums.
Brian McNelis of the IBA said the experience of his members was that this "insurance fraud" was three times higher than previously thought.
The representative body says that in the UK brokers have access to claims databases.
These tools are effective in combating the fraud problem but data protection laws in Ireland mean it is not possible to share data here.
Mr McNelis said: "Although official numbers say that insurance claim fraud occurs in around 7pc of cases, our broker members have suggested that in reality this figure could potentially be closer to 20pc."
He said there was a claims database operated by the Irish Insurance Federation (IIF) but access to this was restricted.
"So in essence we are faced with a situation whereby insurance companies can only access this data when a claim occurs instead of when they are underwriting an insurance policy for a particular individual.
"In order for this to work effectively we would need to build an insurance fraud register which could tie in with the existing database and which would alert insurers to cases of fraud," the IBA boss said.
Insurance fraudsters are driving up the cost of insurance premiums for everyone else, he added.
Michael Horan of the IIF said insurance fraud was costing €100m a year.