Nicola Sturgeon said that the Scottish Government would push for complete control of Scotland's railways - as the train operation becomes nationalised from Friday.

The First Minister said it now wanted control of the infrastructure, which includes the tracks and signals, currently run by Network Rail.

She spoke of the ultimate ambition as she dismissed claims that the new nationalised ScotRail will become "CalMac on wheels".

The First Minister said that the move to public ownership is a "very significant milestone" and "marksa new beginning for ScotRail".

And she added: "Our commitment is clear. We've invested nine billion pounds in the railway since 2007.

"We will continue to press for full devolution of rail powers including full devolution of Network Rail in Scotland so that we can then truly deliver the railway that Scotland wants and deserves."

The services are to be run by a Scottish Government 'arms-length' company after the seven-year stint by Dutch state transport firm Abellio comes to an end.

Ms Sturgeon told MSPs: "It provides an opportunity to modernise and deliver passenger services which are efficient, sustainable, safe, fit for the future, and which reflect the changing world we live in.

"Obviously, from tomorrow services will continue as normal. It's important that we provide reassurance and familiarity to passengers in the immediate term as we recover from the disruption and impact of the pandemic. Later this spring we will watch the national conversation offering rail staff, passengers and communities an opportunity to contribute to the future vision for Scotland's Railway and help shape this new beginning for Scotland."

But Graham Simpson, the Scottish Conservatives' shadow transport secretary questioned whether the rail service would become like the publicly run ferry service.

"We know the SNP is no good at running things, you just have to look at the ferries for that.

"So given that fiasco, rail passengers should be worried that NatRail will turn out to be CalMac on wheels.

"On Sunday, transport minister Jenny Gilruth was quoted as saying from day one, you might not necessarily see anything that looks different, but the major difference is accountability. Well Ms Gilruth obviously didn't get the memo that this government doesn't do accountability. So far, what we do know is that we're going to have rising fares, service cuts and ticket office closures. What part of that is an improvement? "

But Ms Sturgeon hit back: "This government of course, has already delivered significant improvements on our railways and that's even before the railway comes into public ownershi as it will tomorrow."

She then listed a series of towns and villages that had all connected to the rail network since 2019 through the reversal of cuts.

And said in the next three years five more will follow.

"Railway workers in England under the Tories face a pay freeze. A fair pay deal was delivered in October last year for ScotRail staff," she said. "And lastly, of course we've taken action to keep rail fares down. ScotRail fares are on average 20% cheaper than in those areas of the UK governed by the Conservatives."

The debate came as RMT began holding a day of action calling on the Scottish Government to promote and expand all jobs, skills, services and ticket offices connected to the newly nationalised ScotRail.

RMT members were due to gather outside Glasgow Queen Street station at noon, demanding that the new operator “delivers for Scotland’s rail passengers, communities, and workers”.

Ms Sturgeon added: "I think bringing Scotland to public ownership is a historic moment and I am delighted that it is happening under this government. "

Abellio has been running the franchise since 2015 but had its contract ended early amid criticism over cancellations and performance levels.

All ScotRail staff will transfer to the new Scottish government-owned entity.

A new company called ScotRail Trains Limited will run services from April 1, overseen by Scottish Rail Holdings Ltd, a new public body controlled by the Scottish Government.