Scrutiny of the Brexit trade agreement with the European Union has begun after the full treaty was published less than a week before it is due to be implemented.

Legal experts and MPs were poring over the 1,246-page document published on the morning of Boxing Day, as Boris Johnson worked to persuade Eurosceptic Tories to back it as the “right deal” for the country.

The Prime Minister acknowledged to Conservative MPs that “the devil is in the detail” but insisted it would stand up to inspection from the European Research Group (ERG) of Brexiteers, who will assemble a panel of lawyers to examine the full text ahead of a Commons vote.

But the chief executive of the National Federation of Fishermen’s Organisation, Barrie Deas, accused Mr Johnson of having “bottled it” on fishing quotas to secure only “a fraction of what the UK has a right to under international law”.

Mr Deas said the Prime Minister had “sacrificed” fishing to other priorities, with the subject proving to be an enduring sticking point during negotiations.

“Lacking legal, moral or political negotiating leverage on fish, the EU made the whole trade deal contingent on a UK surrender on fisheries,” Mr Deas said.

“In the end-game, the Prime Minister made the call and caved in on fish, despite the rhetoric and assurances that he would not do what Ted Heath did in 1973.”

The share of fish in British waters that the UK can catch will rise from about half now to two-thirds by the end of the five-and-a-half-year transition.

The EU’s 27 member states indicated they will formally back the deal agreed by the UK with Brussels’ officials within days.

It covers trade worth about £660 billion and means goods can be sold without tariffs or quotas in the EU market.

EU ambassadors were briefed on the contents of the deal by Michel Barnier, who led Brussels’ negotiating team in the talks with the UK.

After a highly unusual meeting on Christmas Day – with at least one diplomat wearing a Santa hat and another in a festive jumper – they agreed to write to the European Parliament to say they intend to take a decision on the provisional application of the deal.

The timing of the Christmas Eve deal forced politicians and officials in the UK and Brussels to tear up their plans.

MPs and peers will be called back to Westminster on December 30 to vote on the deal, but MEPs are not expected to approve it until the new year, meaning it will have to apply provisionally until they give it the green light.

The agreement will almost certainly be passed by Parliament, with Labour supporting it, as the alternative would be a chaotic no-deal situation on January 1.

But Mr Johnson is keen to retain the support of the Eurosceptics on his benches who helped him reach No 10.

On Saturday, Conservative former Cabinet minister Theresa Villiers told BBC Breakfast: “I very much hope this treaty stands up to scrutiny and I hope to be able to support it.

“But I was elected on a manifesto which promised to get Brexit done so I need to read (the document) before I can work out whether this actually enables us to do that or whether it traps us in the regulatory orbit of the European Union.”

I truly believe this is the right deal for the UK and the EU

Mr Johnson had earlier messaged Tory MPs on WhatsApp as he tried to get them all on side.

“I truly believe this is the right deal for the UK and the EU,” he wrote, in a message seen by the PA news agency.

“We have delivered on every one of our manifesto commitments: control of money, borders, laws, fish and all the rest.

“But even more important, I believe we now have a basis for long-term friendship and partnership with the EU as sovereign equals.”

He added that “I know the devil is in the detail” but the deal will survive “ruthless” scrutiny from the “star chamber legal eagles”.

The “star chamber” is the nickname given to the panel assembled by the ERG, including veteran Eurosceptic Sir Bill Cash.

Cabinet minister Michael Gove, writing in The Times, said the deal will create a new “special relationship” – a term usually used to refer to UK-US links – and end the “ugly” politics since the 2016 Brexit referendum.

Officials in Brussels and the capitals of EU states are also beginning to scrutinise the deal, with another meeting of ambassadors expected before the new year, possibly on December 28.

The European Commission has also announced a £4.5 billion fund to help regions and industries within the bloc which will be hit by the UK’s withdrawal from the single market and customs union – including fishing communities who face losing out as the UK takes a greater share of stock in British waters.

French Europe minister Clement Beaune said it was a “good agreement” and stressed the EU had not accepted a deal “at all costs”.

Mr Beaune said that British food and industrial products entering the European single market after January 1 will not pay customs duties “but will have to meet all our standards”.

“There is no country in the world that will be subject to as many export rules to us as the UK,” he told broadcaster Europe 1 said.