Speaking in Ballarat on Friday, Mr Andrews said the rail link to Melbourne airport, which Ballarat representative groups say should include a tunnel to separate regional trains from metropolitan services, was still being planned.

As reported last week, Mr Pallas mentioned an above-ground route at a business event.

READ MORE: Ballarat rail line: Tunnel plea after treasurer's comments

"The Treasurer gave a speech where he talked about the fact that there are a number of options, there were four or five corridor options to start with before we nominated Sunshine as the corridor that we would use," he said.

"This project needs to be planned properly, and there'll be people who play politics with it to scaremonger, but we will deliver this project, it'll be under way by 2022, it'll be good value for taxpayers and also an outstanding service.

"Where we can get that double benefit of a mass transit heavy rail link to the airport but at the same time unlock capacity by separating electric and diesel lines, metropolitan and regional lines, and unlock the potential for faster, better services for regional Victoria, we will.

"All the Treasurer was doing was indicating it is a complex issue because there's many different choices you can make - there's $10 billion on the table from us and the Commonwealth Government, we've chosen a corridor but there's lots of different options and sequencing, and making those critical choices is really very important."

Mr Andrews added he had discussed the plan with Prime Minister Scott Morrison at a recent meeting, and the Western Rail Plan, which prioritises separating regional trains from Melton, was also under way.

The state government has also committed more than $500 million to the Ballarat line upgrade project, which is due for completion at the end of the year.

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