Tens of millions of doses of the Covid-19 vaccine manufactured in Belgium will be flown to Britain by military aircraft to avoid delays at ports caused by Brexit, under contingency plans being developed by the government. Both the Department of Health and Social Care (DHSC) and senior sources at the Ministry of Defence (MoD) confirmed to the Observer on Saturday that large consignments would be brought in from 1 January by air if road, rail and sea routes were subject to widely expected delays after that date. Civil servants from the MoD and military planning staff have recently met officials from the government’s vaccine taskforce to discuss the plans, with priority being given to speedy transfer of the doses. “We will do this if necessary. The plans have been discussed,” said a DHSC source. The move shows that ministers are ready for severe disruptions at ports and commercial airports whether or not there is a Brexit deal, and are not prepared to allow the vaccine to be held up in any circumstances. News of the preparations to fly in vials came as it was announced that Brexit negotiations would resume in Brussels on Sunday after Boris Johnson and the European commission president, Ursula von der Leyen, agreed following a telephone conversation that there were still grounds for hope that a deal will be struck in the next few days. In a joint statement, the leaders said they would talk again on Monday evening, with the two sides searching for a breakthrough with just three weeks until the UK leaves the single market and customs union. “In a phone call today, we welcomed the fact progress has been achieved in many areas,” they said. “Nevertheless, significant differences remain on three critical issues: level playing field, governance and fisheries. Both sides underlined that no agreement was feasible if these issues were not resolved. “While recognising the seriousness of these differences, we agreed a further effort should be undertaken by our negotiating teams to assess whether they can be resolved. We are therefore instructing our chief negotiators to reconvene tomorrow in Brussels. We will speak again on Monday evening.” A government source close to the talks said: “There is barely any time left and there is no doubt that this process may not end in agreement. “This is the final throw of the dice. There is a fair deal to be done but it will only happen if the EU is willing to respect the fundamental principles of sovereignty and control.” The European commission’s chief Brexit negotiator, Michel Barnier, tweeted: “We will see if there is a way forward. Work continues tomorrow.” Ireland’s taoiseach, Micheál Martin, pushed both sides to make the compromises necessary to find agreement. He tweeted: “I welcome the fact that negotiators will resume their discussions on an EU and UK trade deal in Brussels tomorrow. An agreement is in everyone’s best interests. Every effort should be made to reach a deal.” Rachel Reeves MP, shadow minister for the Cabinet Office, said: “The British people were promised a deal and, with time running out, we urge both sides to get on with reaching an agreement. “We can then focus on the job at hand, which is securing the economy and rebuilding our country from the pandemic.” The main areas of difference remain over the so-called level playing field arrangements to ensure fair business competition, and EU access to UK fishing waters. Sources close to the negotiation said the situation was serious, with the final political issues proving hard to solve. In London, MPs will debate and vote on the controversial internal market bill on Monday . The government is then due on Wednesday to table the finance bill, containing new clauses that override the withdrawal agreement previously struck with the EU, a move that would effectively mark the end of talks. But there is an expectation among senior diplomats that agreement should be found before then, with EU leaders able as a result to sign off on a deal at a virtual summit of EU leaders on Thursday. The cautiously positive outlook in Brussels contrasts with the recent warnings from Downing Street that a deal is hanging in the balance. UK sources on Saturday said Downing Street hoped for more realism from the EU side after Michel Barnier, the bloc’s chief negotiator, was said to have tabled unacceptable proposals on Thursday. It was claimed the proposals on domestic subsidy control and standards would effectively force Westminster to align with the EU rule book. Brussels was also said to have demanded a 10-year pause on any changes to fishing access for European fleets in the UK’s exclusive economic zone. David Frost, the UK negotiator, has offered a three-year transition period. With or without a deal, businesses will face many extra checks on goods leaving and entering the UK. The prospects of a deal are creating political challenges for both major parties. Leading Conservative Brexiters will be studying any agreement closely for evidence that the UK has given ground on fishing or been tied to the EU’s state aid rules. Many have already rebelled against the government over its coronavirus measures. Some Tory donors who backed Johnson’s bid to become leader over his Brexit stance are also understood to be nervous about his willingness to give ground to the EU in order to secure a deal. UK officials with knowledge of plans to import the vaccines said other ways to transport them would be considered in addition to military planes, including via the express freight service that was set up to carry medicines and medical equipment by road, rail and boat to the UK in 2019, ahead of Brexit. But flying them on military planes would be the fastest and present the least risk of delay, allowing consignments to be flown into military or other airports near centres from where the vaccine could be distributed. Since the Pfizer BioNTech vaccine was approved for use in the UK by regulators last week, 800,000 doses have already been imported via the Channel Tunnel and are being held at secure locations. A total of up to five million doses are expected to come into the country by the end of the year. The health secretary, Matt Hancock, said on Saturday that the vaccine could bring the loosening of restrictions before the end of March. In an interview with the Telegraph, he said he “can’t wait [...] to get back to living by mutual respect and personal responsibility, not laws set in Parliament”. He added: “There’s no doubt that having the vaccine early... will bring forward the moment when we can get rid of these blasted restrictions, but until then we have got to follow them. Help is on its way.” After 1 January, when the EU transition period ends and delays are expected at borders, another 35 million will be transported to the UK. An MoD source said: “If we need to use military planes to bring them in, we will. If the request is made we will be ready.”