Britain and the European Union have made progress towards a post-Brexit trade deal but might be unable to strike an agreement before the December 31 deadline, the UK’s top negotiator said on Sunday as he entered a critical round of new talks. David Frost said there had been some movement recently but significant elements were yet to be agreed, less than seven weeks before the UK ends nearly five decades of economic and political ties with the continent. “There has been some progress in a positive direction in recent days,” Mr Frost said on Twitter. “We also now largely have common draft treaty texts, though significant elements are, of course, not yet agreed. We will work to build on these and get an overall agreement if we can. But we may not succeed.” Several deadlines to strike a deal have already passed but talks started on Sunday in a last-ditch effort to reach agreement before the end of the year. If no deal with the EU is reached by 2021, the UK will at a stroke sever its existing political and trade links with the EU. The UK left the bloc at the end of January but signed up to a transitional pact until the end of the year to give businesses time to prepare for the major overhaul. Employer organisations are pushing the government to strike a deal because of the expected heavy economic effect of Brexit, combined with the fallout from the Covid-19 pandemic. But talks have been stymied by issues including fishing rights and state aid. Both sides “recognise that time is very short”, Environment Secretary George Eustice told Sky News on Sunday. “This needs to be a week when things move, when we break through some of these difficult issues, and get a resolution, and at least have some sort of headlines of an agreement,” he said. “Otherwise it gets quite difficult and we do start to run out of time to implement it.” Officials in Brussels insist that reaching a deal will require UK Prime Minister Boris Johnson to move first, a stance their British counterparts reject. Irish Foreign Affairs Minister Simon Coveney said negotiators were running out of time, and “this is move week”. Mr Johnson’s government has been embroiled in internal strife this week with his chief adviser Dominic Cummings – an arch-Brexiteer who led the campaign to leave the EU – resigning, along with another adviser, Lee Cain.