The green port model adapts the UK Government’s freeport proposals, offering a package of tax and customs reliefs. Operators and beneficiaries will be required to commit to adopting Fair Work First criteria and contribute to Scotland’s just transition to net zero.

The Scottish Government expected to launch the bidding process for green ports in Scotland this month, in partnership with the UK Government.

Mr McKee said: “I have been clear that green ports will contribute to the Scottish Government’s ambitions to deliver fair work and enable a just transition to net zero. Our Applicant Prospectus, which has been drafted jointly with the UK Government, reflects these dual objectives.

“We are ready to launch the bidding process and, as far as the Scottish Government is concerned, the Applicant Prospectus is ready for publication now.

“We have been working with the UK Government on this in good faith. Regrettably, it would now appear that there is a lack of willingness on the part of the UK Government to sign up to our green port ambitions on fair work and net zero.”

He added: “As we are now fast approaching the start of the pre-election period in Scotland on 25 March, there is the real prospect of a potentially damaging delay until after the Scottish Parliament Election in May.

“If we do not have confirmation that the UK Government is ready to launch the Applicant Prospectus by close of business on Monday 22 March, we may have to conclude that the UK Government has effectively withdrawn from this process.

“If that is the case, I would call on them to confirm that and explain it to Scotland’s ports, airports, local authorities and the wider business community.”