European Union ambassadors are convening on Christmas Day to assess the free-trade deal the bloc struck with the UK following nine months of negotiations. The EU’s chief negotiator, Michel Barnier, will update the diplomats on the agreement, reached after months of fraught talks on fishing rights and business rules. Boris Johnson has hailed the deal as a “new beginning” for the UK. But a major fishing organisation has accused the prime minister of sacrificing the industry to reach an agreement as the deadline for leaving EU trading rules loomed. The prime minister is still waiting to hear the verdict of Eurosceptic MPs within his own party, some of whom have privately voiced concerns that the deal did not go far enough. The Labour leader, Keir Starmer, said it was a “thin agreement” but that his party would back it as the only alternative to no deal, meaning it should win approval in the Commons. After the deal was announced on Thursday, EU nations said they supported the outcome. It is widely expected that they will unanimously back the agreement, a prerequisite for its legal approval. The European parliament needs to ratify the deal but it is unlikely to do so until the new year, meaning its application will formally be provisional until then. MPs and peers will be called back to Westminster on 30 December to vote on the deal. Sebastian Fischer, a spokesman for the German presidency of the Council of the EU, joked that he was looking forward to the diplomats’ meeting “because nothing is more fun than to celebrate Christmas among socially distanced colleagues”. “Thank you Brexit,” he added. The French Europe minister, Clément Beaune, said it was a “good agreement” and stressed the EU had not accepted a deal “at all costs”. He told the broadcaster Europe 1 “we needed an agreement less than the British” as “for them, it was a vital need”. “There is no country in the world that will be subject to as many export rules to us as the UK,” he said. A summary of the document has been published by the government. The full document, which is about 1,500 pages, is supposed to be published soon. Johnson used his Christmas message to sell the deal to a public weary of Brexit after years of acrimonious wrangling since the 2016 referendum. Clutching a sheaf of papers he said: “I have a small present for anyone who may be looking for something to read in that sleepy post-Christmas lunch moment, and here it is, tidings, glad tidings of great joy, because this is a deal. “A deal to give certainty to business, travellers and all investors in our country from January 1. A deal with our friends and partners in the EU.” The prime minister has claimed the deal meets the goals set out during the 2016 campaign to “take back control”. This includes an increase in the share of fish in British waters that the UK can catch, rising from about half now to two-thirds by the end of the five-and-a-half-year transition. At a Downing Street press conference on Christmas Eve, Johnson said “as a result of this deal [we will] be able to catch and eat quite prodigious quantities of extra fish”, with £100m for the UK fishing industry to modernise and expand. Fishing organisations have disagreed with Johnson’s assessment. Barrie Deas, chief executive of the National Federation of Fishermen’s Organisations, said there would be “frustration and anger” across the industry. “In the end it was clear that Boris Johnson wanted an overall trade deal and was willing to sacrifice fishing,” he told PA news agency. French politicians have expressed concern that the deal postpones wrangles over fishing rights, instead of solving them. Boulogne-sur-Mer’s mayor, Frédéric Cuvillier, said the agreement left much obscured. “Relief for our fishermen, but what will be the impact on stocks? Who, for example, will be handling the controls? And over what time?” he told Europe 1 radio. “The only certainty today is that we need to find, during the transition period, more deals within the deal.”