RICHARD Branson's rail firm is on a collision course with SNP ministers, amid claims a core transport policy is threatening high speed rail routes to Scotland.

Virgin Trains said around a third of rail journeys between Edinburgh and London were at risk if the Scottish Government abolished air passenger duty (APD) because train bookings would inevitably fall.

Virgin also said the move had potentially fatal consequences for long-term plans to bring high-speed rail north of the border, as well as a negative impact on environmental targets.

The Scottish Government wants to cut the APD by 50 per cent, with the reduction set to start when it introduces a replacement in April 2018. Ministers want it scrapped entirely by the end of the current parliament in 2021 amid pressure from airport operators to bring APD to an end as soon as possible. Ministers and Scots airports hope reducing the levy will increase the number of direct flights to and from Scotland. But ahead of giving evidence at Holyrood's Finance Committee on Wednesday, Virgin, which operates on the East Coast and West Coast inter-city routes between Scotland and London, said the move could have catastrophic consequences for the country's rail ambitions.

In a written submission, it said the abolition or reduction of the tax could have a "significant impact on rail passenger numbers which have grown significantly over the last 20 years, particularly betwee Scotland's central belt and London".

It added: "Virgin Trains' own initial modelling suggests that as much as a third of the southbound Edinburgh-London rail market could be lost to air if APD were abolished on this route and the tax reduction was passed on in reduced fares.

"This would represent a negative modal shift, lead to a significant increase in carbon emissions, reduce funds available to Government through franchise payments and undermine the long-term growth of the cross-border rail market and business case for developing a high-speed rail network to Scotland."

Virgin Trains also said a policy is required which distinguishes between domestic travel, where flights and rail are both options, and international routes."

Airlines and airports have been supportive of the principle of scrapping APD. Research published by Edinburgh Airport, which it said had been verified by BiGGAR Economics, found a 50 per cent cut to APD in one move in April 2018 would have meant an additional 18 million passengers using Scotland's airports by 2021.

It said: "This will create nearly 10,000 new jobs in Scotland, add more than £300million Gross Value Added per year to the Scottish economy, and generate a range of tax revenues that will comfortably exceed the cost of the cut.