London, July 10 : "Significant divergences" remain between the European Union (EU) and the UK on a post-Brexit trade deal following three-days informal talks in London, the bloc's chief negotiator Michel Barnier has said. Taking to Twitter on Thursday night, Barnier said: "This week's discussions confirm that significant divergences remain between the EU and UK. We will continue working with patience, respect and determination. "Regardless of the outcome, there will be inevitable changes on 1/1/21." Both sides had agreed to "intensify" negotiations last month and held the first face-to-face talks since the coronavirus pandemic at the beginning of July, reports the BBC. If they are unable to reach a deal by the end of the transition period at the end of the year, the UK will leave the EU's single market and the customs union without any agreement on future access. The UK has ruled out extending the December deadline to reach a deal. On Wednesday, Barnier said the discussions had been "useful" and the team was "negotiating in good faith". He said they were "working hard for a fair agreement" with the UK, including on fisheries and the "level playing field" arrangements designed to prevent the UK undercutting the EU by lowering standards and increasing state subsidies. The two sides have been deadlocked over the issue of fishing rights - an area where they had previously pledged to find agreement by last month, said the BBC report. The EU wants to uphold its existing access to British waters for vessels from member states, to avoid economic disruption for their fishermen. But the UK wants to hold annual talks with the bloc over access to its waters, as it currently does with nations such as Norway. Meanwhile, European Commission spokesman Daniel Farrie told reporters they were "working hard to overcome the significant divergences that remain between us". "Meetings will continue in Brussels next week and the next round of negotiations will take place in the week of 20 July in London," he said. According to the Downing Street, the UK's Brexit negotiator David Frost will travel to Brussels for further discussions next week before formal negotiations resume in London in about a week's time. /IANS