MSPs have backed plans for Holyrood to take control over Air Passenger Duty next year.

The parliament approved the general principles of the Scottish Government’s Air Departure Tax (Scotland) Bill by 112 to four in a preliminary Stage One vote, with Greens abstaining.

However there was widespread criticism of the SNP’s specific plan to spend £160m a year to halve the air tax by 2021 and abolish it completely when public finances allow.

Passengers currently pay £13 or £26 on standard short-haul flights, and £73 or £146 for longer-haul flights, with private jet passengers paying up to £438 each.

The SNP say a cut will bring more routes to Scottish airports and boost jobs and the economy.

However opponents say there is little evidence for an economic uplift, and warn the increased pollution will undermine the SNP’s own climate change targets.

Holyrood's Finance Committee also criticised the lack of evidence, after Finance Secretary Derek Mackay he had not ordered an economic assessment of the policy.

He has now promised to do so, although it will not be published until after the Bill is passed.

When Air Passenger Duty is devolved in 2018, it will be renamed Air Departure Duty.

Mr Mackay yesterday insisted there would be "strong economic benefits" to the cut.

But Green MSP Patrick Harvie said there was a "central contradiction in the Bill", arguing an economic analysis was “surely what you do before deciding your tax policy”.

He said: "What on earth is the rationale for deciding on a tax policy before you have a clue what the impact of it is actually going to be?"

Mr Mackay said the Alex Salmond-era tax cut was “a longstanding commitment”, and a “key part” of the Government's economic strategy that was "especially important” given Brexit.

The Finance Secretary said: "Scotland's airports are competing on a world stage to secure new routes and capacity, and reducing the tax burden helps ensure there is a more level playing field with many other European airports competing to secure the same airlines and similar routes. New routes will enhance business connectivity and tourism."

Labour's Neil Bibby said it was “absurd” for the SNP to prioritise abolishing aviation tax when essential public services such as health and education were facing cuts.

He said: “The axe will have to fall somewhere. Will it be schools, hospitals, bus pass cuts for the elderly? It's time for the SNP to be honest about their plans."

Tory Murdo Fraser said the overall 50 per cent cut should be targeted on removing the tax from long-haul flights.