Four out of five complaints by whistleblowers to the corporate watchdog last year were dismissed largely due to "insufficient evidence", the regulator has said.

The Australian Securities and Investments Commission said, following preliminary inquiries, about 80 per cent of disclosures from whistleblowers were assessed as requiring "no further action".

The watchdog said this was largely due to insufficient evidence. In some cases it determined that "another agency, law enforcement body or third party", such as a liquidator, was better placed to deal with the issue or was already taking action.

According to information in its ASIC's annual report, of the 146 complaints it received last financial year only about 10 per cent of matters were referred on for compliance, surveillance or investigation.