Vic premier apologises for train chaos

Victorian Premier Daniel Andrews has apologised to commuters after a false fire alarm brought Melbourne's train system to a standstill, but says the system worked as intended to keep people safe.

Metro Trains' Flinders Street control centre was evacuated after the alarm sounded after 8am on Thursday, stopping trains right across the network.

Staff have returned, but Metro says delays of up to 30 minutes are expected through the morning while a backlog of trains clears.

Had there been a real fire, Mr Andrews says, a back-up control room would have kicked in straight away.

"Everything would have switched to that redundancy, to that second back-up, if it had been an actual fire," he told reporters.

But it was a false alarm, so the system was back up and running within a few minutes, Mr Andrews said.

"Safety has to come first and I do apologise, obviously ... but the protocols are in place and they worked," he said.

Greens transport spokeswoman Samantha Dunn said the heads of Metro and Public Transport Victoria needed to take responsibility for the failure and ensure it did not happen again.

"The entire system cannot just grind to a halt because a fire alarm goes off in the control building," Ms Dunn said.

"A parliamentary inquiry can hear details of what happened and the options available to avoid this chaos being repeated."

Commuters who were left in the lurch took to social media.

Many said they were stuck on trains between stations while others said they were told the train would stop at the next station.

Unimpressed commuter Dana McKay vented via Twitter: "I never fare evade but when you have nothing in place to deal with emergency I can see why people do."