THERESA May has been accused of “a massive sell-out” of Scotland’s fishermen after agreeing to Britain abiding by EU fishing quotas during the 21-month implementation period.

As the UK Government announced it had agreed with Brussels the basis of a transition deal through to the end of 2020, accusations of betrayal over fishing rights came from different quarters – a charge denied by Downing Street.

Ruth Davidson faced calls from the SNP to apologise over her “shame-faced” breaking of a promise to help safeguard Scottish fishermen’s rights.

But the Scottish Conservative leader issued a warning to the Prime Minister; that if the UK did not take back full control of its waters post December 2020, then she could not back the final Brexit deal.

David Davis told a press conference in the Belgian capital that the UK had agreed the basis of a deal covering the implementation period, which now looks set to be agreed by the EU27 at this Thursday’s European Council meeting.

The Brexit Secretary said as part of that deal there would be “specific safeguards” on annual fishing negotiations, which take place each December covering the following 12 months.

The deal means:

*Britain will abide by the quotas agreed in December 2018 for the following year;

*from December 2019 for the following 12 months the EU will have to “consult” with Whitehall but the UK’s share of the total catch will not be changed, “protecting the interests of the UK fishing community” and

*from 2020, the UK will negotiate fishing opportunities as an independent coastal state, “deciding who can access our waters and on what terms”.

But Bertie Armstrong for the Scottish Fishermen’s Federation said what Mr Davis had agreed fell “far short of an acceptable deal”.

He explained: “We will leave the EU and leave the Common Fisheries Policy[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.”

Mr Armstrong added: “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.”

Nicola Sturgeon tweeted: “This is shaping up to be a massive sell-out 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.”

Earlier, asked if the PM was prepared to “sell out” Scottish fishermen to get an EU deal, her spokesman said: “No.” He added: “There is an implementation period; once we leave the EU, we will be taking full control of our waters, yes.”

He pointed to Mrs May’s Mansion House speech in which she said: “We are also leaving the Common Fisheries Policy.

“The UK will regain control over our domestic fisheries management rules and access to our waters. But as part of our economic partnership we will want to continue to work together to manage shared stocks in a sustainable way and to agree reciprocal access to waters and a fairer allocation of fishing opportunities for the UK fishing industry. And we will also want to ensure open markets for each other’s products.”

Last week, Michael Gove together with Ms Davidson penned an article, saying they both supported the UK leaving the CFP when it withdrew from the EU and that it was “vital” to regain control of UK waters.

“We want the UK to become an independent coastal state, negotiating access annually with our neighbours. During the implementation period, we will ensure that British fishermen’s interests are properly safeguarded.”

The Environment Secretary, a leading Brexit campaigner, has made taking back control of UK waters a central plank of his argument for leaving the EU.

It is thought that after the EU early last week linked directly getting a trade deal with the UK to retaining fishing rights in UK waters for European fishermen, he raised concerns at Tuesday’s Cabinet meeting while officials from his department were in Brussels informing the UK’s Brexit negotiating team.

Following Mr Davis’s statement, Fergus Ewing, the Scottish Government’s Rural Economy Secretary, also went on the attack, suggesting the Scottish Conservative leader should be “shame-faced for her fastest broken Brexit promise yet”.

He said: “Just last week she said: ‘Britain will leave the CFP as of March 2019.’ Now we know not only will the UK have to abide by CFP rules during the transition period, it will lose the voting rights it has now. The Tories have delivered the worst possible outcome for Scotland’s fishing industry,” declared Mr Ewing.

He added: “It is outrageous that Ruth Davidson and Michael Gove could have issued such a misleading statement last weekend when they must have known what was about to happen and they must both now apologise for their broken promise.

“The Tories have demonstrated once again that for them Scottish interests are expendable. They are so arrogant they now think they can do whatever they want to Scotland and get away with it.”

Ms Davidson said that the UK wanted to gain control over its waters from as early as the end of next year but the EU was not willing to move on this.

“That we now have to wait until 2020 to assume full control is an undoubted disappointment,” admitted the Edinburgh MSP.

“Having spoken to fishing leaders today, I know they are deeply frustrated with this outcome. There is no ignoring the fact that this falls short of what they had hoped for in the short term.”

Ms Davidson said she made clear to them that she would continue to “do everything in my power to ensure their interests are protected during the implementation period and beyond”.

The party leader made clear any attempt by the EU to use the implementation period to weaken the Scottish fishermen’s hands would be a breach of the agreement.

“Over the long-term, today's agreement makes clear that, from 2020, the UK will be an independent coastal state, deciding who can access our waters and on what terms. 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,” she added.

Her colleague, the Borders MP John Lamont, bemoaned how the implementation agreement "in no way matches what I hoped to achieve from this process; it will mean our fishing waters continue to be controlled by Brussels for much longer than expected".

He stressed after the implementation period was over, full control over domestic waters must come back to the United Kingdom from Brussels. “Anything less will be a betrayal of our fishing communities who voted for Brexit in large numbers,” added Mr Lamont.