FRV investigates claims firefighters accessed an unauthorised area of Metro Tunnel

A view inside the new Town Hall Station, part of the Metro Tunnel project.

Firefighters accessed an unauthorised area of the Metro Tunnel on its opening day and triggered an alarm. (ABC News: Toby Hussey)

In short:

The United Firefighters Union has claimed firefighters accessed the Metro Tunnel on its opening day for operational reasons, but Fire Rescue Victoria (FRV) says there was no site visit planned.

The incident — which is being investigated by FRV — triggered an alarm and caused some delays and other minor issues.

The union has previously raised safety concerns about the new tunnel, which the regulator, the state government and FRV have rejected.