The Australian Securities and Investments Commission has admitted it has been gagged by big insurance companies from releasing the names of life insurers denying as many as one in three customer claims.

The revelation was made during ASIC's appearance before the parliamentary Standing Committee on Economics on Friday.

ASIC's senior executive for insurers, Michael Saadat, said the corporate watchdog used its compulsory powers to extract the information from insurance firms.

"They can consent to us publicly revealing the information but they haven't done so. The insurers we have spoken to so far have expressed significant concern," Mr Saadat told the committee.