The Victorian premier has slammed firefighters who entered the Metro Tunnel on Sunday, saying their actions were “potentially deadly”, despite the union’s claims they were there for operational reasons.

On Sunday, Fire Rescue Victoria (FRV) said it was advised by Metro Tunnel Melbourne that its “firefighters accessed an unauthorised area of the Metro Tunnel”.

“This access triggered a security alarm which temporarily delayed the trains and resulted in the attendance of Metro Trains Security,” a spokesperson said in a statement on Sunday.

A Metro Tunnel spokesperson said the alarm was triggered at 11:30am when “unauthorised trespassers” managed to gain access to an area near Hawksburn Station.

On Monday, Victorian Premier Jacinta Allan condemned the incident, alleging the firefighters had trespassed.

“Anyone who trespasses into a live operating environment is undertaking a potentially deadly set of actions,” Ms Allan said.

“A live rail operating environment is not a place to play games. It is a place that you should always be putting safety first, which is why trespassing is taken very seriously.”

Premier Jacinta Allan and Gabrielle Williams, dressed in red, ride up an escalator at Anzac Station.

Victorian Premier Jacinta Allan Transport Infrastructure minister Gabrielle Williams at the opening of the Metro Tunnel. (AAP: Erik Anderson)

The United Fire Fighters Union said firefighters had entered the tunnel “to conduct a building inspection”. 

“This was an operational matter with firefighters conducting an urgent familiarisation drill,” a union spokesperson said on Monday. 

“During approximately half-an-hour spent in the Eastern Portal, firefighters inspected the Fire Control Room, potential hazards such as UPS power supplies, high voltage sub stations and battery energy storage banks and the very unique suppression systems.

“The visit was vital for firefighters’ knowledge of the environment in which they will be expected to conduct rescues and will enable them to carry out their roles in an emergency situation safely, effectively and efficiently.”

But when asked by the ABC, FRV said the incident was not linked to any official drill.

“FRV can confirm there was no pre-organised official drill or site visit planned for the Metro Tunnel on Sunday 30 November,” a spokesperson said.

An internal view of the Metro Tunnel.

The Metro Tunnel opened on Sunday after years of construction. (Supplied: Infrastructure Victoria)

FRV said it was investigating the incident, while Victoria Police said it had not received a complaint and was not investigating the matter.

Previously, the United Firefighters Union had written to the national rail safety authority to assess the validity of accreditation given to run services in the underground network.

It raised safety concerns claiming thousands of portable radios used by FRV failed to connect to the antenna systems used by emergency services when an unknown number of them were tested in the tunnel.

The regulator, the state government and FRV all rejected the union’s claims. 

Incident caused delays and other impacts

The 9-kilometre train tunnel opened on Sunday with more than 70,000 passengers making the trip through five new inner city stations. 

The new stations run under the CBD, connecting the Sunbury, Cranbourne and Pakenham lines. 

Trainspotters lined up at Sunbury from as early as 6am to get a spot on the inaugural service and cheers rang out at various parts of the journey.  

The tunnel will allow for an additional 240 weekly services during off-peak times with the full timetable coming into effect in February. 

A train services map with a line highlighted in blue.

The Metro Rail Tunnel features five new underground stations around Melbourne’s CBD.

  (Supplied: Victorian government)

A Metro spokesperson said the opening of the tunnel was overall “a great success”.

“Opening Metro Tunnel is the biggest change to our rail network in more than 40 years and as we commenced the Summer Start timetable, we are now able to test the new infrastructure and technology in real world conditions — so bugs can be ironed out,” the spokesperson said. 

Metro said there were a few minor issues on opening day, including a train that overshot the platform at Anzac Station just before midday.

Screen doors also did not operate correctly at times and a few escalators needed minor adjustments throughout the day.

Metro Trains CEO Raymond O’Flaherty said the incident involving the firefighters caused some of these issues.

“After that trespassing incident, we had to run under caution for a number of minutes, [to] make sure everything was back running safely and securely,” he said.

“We actually switched from automatic mode and into manual mode. And during that 20-25 minute period one of our services didn’t berth correctly at the station.”

Mr O’Flaherty said some “glitches” were to be expected in the beginning.

“We’re now learning for the first time … we fully expect to see these glitches along the way as we build our confidence and get ready for the first of February,” he said.