THE Scottish Government is "committed" to free bus travel for under-19s, as promised in the budget, the Finance Secretary has said.

Speaking to the PA news agency, Forbes rubbished claims by the Scottish Conservatives that their promise to the Greens may not come to fruition.

As part of the budget process, the Scottish Government had to negotiate with other parties to pass its legislation through Holyrood.

For the fourth straight year, the Scottish Government was helped by the Greens to pass its plans.

It has resulted in a £173 million deal for the 2020-21 financial year that led to increases in spending on policing, climate change and local government.

The headline demand from the Greens was the implementation of free bus travel for young people aged 18 and under, which Forbes gave an "in principle commitment" to implement.

A letter sent to Greens co-leader Patrick Harvie and MSP Mark Ruskell pledged £15 million to look at the feasibility of the scheme, although Forbes said some of that funding will pay for the early months of the scheme - due to come into force in January.

Scottish Conservative MSPs questioned the language used in the commitment, claiming the Scottish Government was looking to throw away the promise.

Forbes said: "We wouldn't have committed to initial investment if we didn't believe that it was a good policy.

"We've already identified several streams of work around how it operates, consulting particularly young people around what they want to see and also inevitably around the due diligence and the legalities, which we have to do."

She added: "In the budget statement, I gave a commitment to begin that work but any new policy has to be subject to due diligence."

The Finance Secretary refused to give a timetable for the confirmation of the scheme going ahead - saying only she hoped the preparatory work would continue "at pace".

Forbes added: "We're committed to trying to make this work."

During the stage one debate in Holyrood, 24 hours after the agreement was reached with the Scottish Greens, Tory finance spokesman Donald Cameron and his predecessor Murdo Fraser both cast doubt on the promise.

Tory MSP Murdo Fraser told PA: "The SNP hasn't committed to introducing free bus travel for under 18s, they have only committed to investigating it.

"The Scottish Green Party appears to be the only group of people still fooled by this ploy.

"The only question is when will Kate Forbes drop the pretence and finally admit that it's not going to happen."

Harvie said: "The policy of free bus travel for young people in Scotland was hard-won by the Scottish Greens in budget negotiations.

"It will be a truly transformational move, saving struggling families money, widening opportunities for people starting out in life and encouraging people to leave their cars at home.

"We know this policy will work and can be achieved on the timescale set out in our agreement."