The number of authorised officers out in force throughout the network doubled from Friday, with a particular focus on regional interchange stations and Southern Cross Station.

Meanwhile, Victoria Police's Operation Guardian will see 200 police officers monitoring key arterials, back roads and public transport networks to ensure all travel into regional Victoria is for lawful reasons.

The Department of Transport said there would be strong coordination and joint patrols between public transport staff and police and anyone who was 'deliberately, obviously or blatantly' flouting travel restrictions would face a fine of $5452.

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While no travel restrictions are in place for regional Victoria, Melburnians only have five reasons to leave home.

Department of Transport head of transport services Nick Foa said the blitz would protect regional Victoria's freedoms.

"We're ramping up our efforts to protect the hard-won freedoms of regional Victorians and will have double the number of Multi Modal Public Transport Authorised Officers out on the network," he said.

"Our officers will be stationed at regional and metropolitan stations, including Southern Cross, to support Victoria Police's Operation Guardian and making sure people are travelling for one of the five permitted reasons.

"Our message to Melburnians is clear - do not travel to regional Victoria for the wrong reasons - you will be caught and turned away."

The blitz comes as dozens of V/Line services were affected on Friday following a trainer driver testing positive to COVID-19.

A second V/Line employee was also revealed to have tested positive on Friday afternoon, with more than 160 drivers and operations staff required to isolate.

The driver is a trainer who worked on a Gippsland service and spent time in the staff room at Southern Cross Station.

V/Line said 50 services were cancelled on Friday afternoon and evening, with coaches replacing trains on most lines.

At least nine services on the Ballarat line were affected, while services have also been affected on the Bendigo, Geelong, Gippsland and Seymour lines.

V/Line said the biggest impact was to its locomotive hauled services, which operate Warrnambool, Swan Hill and Albury services, along with a small number of Geelong, Bacchus Marsh and Bairnsdale services, due to the additional staff required to operate these services.

Services are also expected to be impacted across the weekend.

Minister for Public Transport Ben Carroll said 20 V/Line services had been disrupted on Friday morning and the disruptions would reach 100 by the end of the day.

"This one individual did enter the staff room at Southern Cross Station and that has impacted up to 100 staff at this stage is our forecast," Mr Carroll said on Friday morning.

"We're working through all the disruptions throughout today. We've got 36 coaches, five are already out in use supporting commuters on the regional network.

"We'll try to minimise disruptions as much as possible come Monday, but urge all commuters to look at the PTV app, monitor disruptions and also do the QR code, always wear a mask on PT and use your Myki card where appropriate."

For more information about V/Line service disruptions, visit vline.com.au.

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