The announcement sparked a furious row between Scottish Tories and Downing Street, with Ruth Davidson warning that her MPs could vote against the final Brexit deal unless it contains firm guarantees that the UK will take full control of fishing rights in its waters after 2020.

One Scottish Conservative MP compared the transition deal to a “pint of cold sick”.

Brexit Minister David Davis and the EU’s chief negotiator Michel Barnier announced the agreement of a 21-month post-Brexit transition in what was supposed to be a victory for Theresa May’s government, giving reassurance to businesses and setting the UK free to seek trade deals with the EU and countries around the world.

Brexit minister David Davis (left) and EU chief negotiator Michel Barnier address a press conference following a landmark deal on transition arrangements. Picture: AFP

But the announcement provoked anger from the UK fishing industry, which had asked for a shortened transition period ending in 2019, and from Scottish Tory MPs who believed that a quick exit from Common Fisheries Policy (CFP) rules was  possible. In December, Environment Secretary Michael Gove told MPs: “It’s not that fishing is outside the transition period, but that there is a specific transition period for fishing of nine or ten months.”

Fishing industry leaders accused the UK government of trading away sovereignty over British waters and demanded written assurances about the content of the final Brexit deal, while Nicola Sturgeon leaped on what she called a “massive sellout”.

Scotland’s Rural Economy Secretary Fergus Ewing accused the Conservatives of delivering the “worst possible” deal for the sector.

In a joint press conference with the EU chief negotiator, Mr Davis hailed the agreement as confirmation that the UK could negotiate trade deals during the transition. The pound rose by more than a cent against the US dollar in response to the announcement.

Despite being shorter than requested by the UK government, Mr Davis said the transition period ending in December 2020 was “near enough the two years we asked for”.

The transition is contained in the full withdrawal agreement, which was unveiled yesterday and colour-coded to show that much of it has already been agreed.

On the border between Northern Ireland and the Republic, Mr Barnier said more work was needed, but that the two sides had agreed how the issue would be dealt with during the remaining negotiations. He said they had agreed the EU’s controversial “back stop position”, which would see Northern Ireland effectively remain part of the single market if there was no wider agreement, would form part of the legal text of the withdrawal agreement.

“The backstop will apply unless and until another solution is found,” he said, adding that because “nothing is agreed until everything is agreed”, the UK’s Brexit deal hung on whether that solution can be found by October.

In a major concession by the UK, Mr Barnier said that there had been “complete agreement” on future citizens’ rights, including that EU citizens arriving in the UK during the transition period will be eligible for permanent residence on existing terms.

“British citizens and European citizens of the 27 who arrive during that transition period will receive the same rights and guarantees as those who arrived before the day of Brexit,” he said.

The UK will no longer take part in quota-setting meetings, but will be consulted by the EU during the transition and will have its quota frozen for 2020.

Responding to the announcement on fishing, Scottish Fishermen’s Federation chief executive Bertie Armstrong said: “This falls far short of an acceptable deal. We will leave the EU and leave the CFP, but hand back sovereignty over our seas a few seconds later.

“Our fishing communities’ fortunes will still be subject to the whim and largesse of the EU for another two years.

“Put simply, we do not trust them to look after us. So we issue this warning to the EU: be careful what you do or the consequences later will be severe. To our politicians we say this: some have tried to secure a better deal but our governments have let us down.

“As a consequence, we expect a written, cast iron guarantee that after the implementation period, sovereignty will mean sovereignty and we will not enter into any deal which gives any other nation or the EU continued rights of access or quota other than those negotiated as part of the annual Coastal States negotiations.”

Ms Sturgeon tweeted: “This is shaping up to be a massive sellout of the Scottish fishing industry by the Tories. The promises that were made to them during #EUref and since are already being broken - as many of us warned they would be.”

Ruth Davidson admitted the terms of the deal fell far short of what the sector had hoped for. “The EU was not willing to move on this,” the Scottish Conservative leader said in a statement. “That we now have to wait until 2020 to assume full control is an undoubted disappointment.

“I am more determined than ever to ensure that this long-term prize for our fishing industry is seized. So I should make it clear today that I will not support a deal as we leave the EU which, over the long-term, fails to deliver that full control over fish stocks and vessel access.”

Scottish Tories at Westminster made clear their anger, with the Moray MP Douglas Ross saying “it would be easier to get someone to drink a pint of cold sick than try to sell this as a success”.

Borders MP John Lamont said: “After the implementation period is over, full control over our waters must come back to the United Kingdom.”

Brexit deal sparks furious row over Scotland's fishing industry