The Star Entertainment Group faced a significant market value drop of over $300 million as the New South Wales casino regulator unexpectedly initiated a second probe into its operations.

Shares plummeted more than 20% after the Independent Casino Commission initiated a second inquiry.

The company expressed readiness for an "objective forum" to showcase its capability to regain suitability.

The current concern revolves around the leadership team's capability to execute remediation programs and address cultural issues.