(Bloomberg) -- U.K. and European Union officials will resume face-to-face trade negotiations this weekend amid last-minute warnings from both sides of large disagreements that could scuttle a trade deal.Prime Minister Boris Johnson said there are “substantial and important differences to be bridged” -- a sentiment echoed by the EU’s chief negotiator, Michel Barnier. The pound extended its fall, hitting its lowest against the euro in a week.Each side says the onus is on the other to make a decisive move if a deal is to be reached. With little more than a month before the U.K. leaves the bloc’s single market -- with or without an accord -- time is now running short. If no agreement is reached, millions of consumers and businesses will face disruption and additional costs from Dec. 31.“Everybody is working very hard -- but, clearly, there are still substantial and important differences to be bridged,” Johnson said in a pooled television interview on Friday. “The likelihood of a deal is very much determined by our friends and partners in the EU. There’s a deal there to be done if they want to.”The last-minute saber-rattling doesn’t necessarily mean the two sides will fail to reach a deal. Over the course of almost four years of negotiations, both the EU and U.K. have repeatedly talked down the prospects of any agreement as a tactic to put pressure on each other and politicians at home.Diplomatic BriefingAn accord could yet be reached as soon as next week, according to three EU officials -- but they cautioned that the bloc is still to be fully convinced that Johnson is ready to sign up to any agreement. The talks could even run on until the following week, they added.“It is late, but a deal is still possible, and I will continue to talk until it’s clear that it isn’t,” Britain’s chief negotiator, David Frost, tweeted. “But for a deal to be possible it must fully respect U.K. sovereignty.”In a private meeting on Friday, Barnier told diplomats from the bloc’s 27 member states that he isn’t particularly optimistic about securing a deal -- but he will continue to try for a few more days, according to officials with knowledge of the discussions. Unless the U.K. takes the necessary decisions quickly, he warned, reaching an accord will be all but impossible, one EU diplomat briefed on the meeting said.Talks between the sides have long been deadlocked in three key areas: access to British fishing waters, the level competitive playing field, and how any agreement will be enforced. Barnier told the ambassadors that the disagreements over these three subjects remain large.After briefing fishing ministers from the EU’s coastal states, Barnier will travel to London later on Friday for face-to-face negotiations to resume on Saturday.Those meetings had to be suspended last week, and Barnier forced to self-isolate, after an EU official involved in the negotiations tested positive for the coronavirus. The Frenchman had warned Frost that there was little point in him traveling to continue talks if the U.K. wasn’t prepared to give ground.Quarantine Ends“My team and I are no longer in quarantine,” Barnier said in a Tweet. “Physical negotiations can continue,” he added, before warning that the “same significant divergences persist.”With the outcome of the talks still uncertain, ambassadors called on the European Commission to start preparing contingency measures should the negotiations collapse.Any deal will need need to be ratified by both the European and British parliaments, meaning one has to be agreed weeks before the end of the post-Brexit transition period on Dec. 31.(Adds Frost comment in seventh paragraph.)For more articles like this, please visit us at bloomberg.comSubscribe now to stay ahead with the most trusted business news source.©2020 Bloomberg L.P.