Brexit negotiations are "going down to the wire," European Union officials said, with only 10 days remaining for a deal to be struck. British and EU politicians are braced for working over the Christmas holiday period as they grind their way through the details of a lasting trade pact. It appears that the two sides remain at odds, despite British sources suggesting at the weekend that an agreement was close with only fishing rights as the major sticking point. EU sources contradicted this, saying they were "very unhappy" about the measures being discussed to prevent Britain undercutting Europe on tax, labour and environmental rules. Negotiations are urgent, with the deadline of January 1 approaching when Britain will leave the EU single market and customs union. The talks were overshadowed by the transport chaos brought on by the new variant of Covid-19 that has emerged in Britain. Negotiators remained in Brussels on Monday, with talks still blocked over the right of European crews to continue fishing in Britain's rich waters, as well as concerns over fair trade rules. Without a deal, Britain's links to the EU will end with a new tariff barrier after half a century of EU membership. Time is now limited to get any potential agreement ratified by both the European and British parliaments. “Political games from Westminster have wasted too much time,” said German MEP Manfred Weber, who warned that members of the European Parliament would take their time and not “rubber stamp” a text. However, Mr Weber also said the respective parliaments “will remain constructive partners” and that “alternative procedures are possible”. European sources said any agreement reached in the next few days could involve a provisional implementation of a pact, with MEPs ratifying it in January. Britain has been effectively cut off from the world after Prime Minister Boris Johnson said a highly contagious mutation of the virus was spreading. With many air and sea links cut, travellers were stranded and goods prevented from crossing the Channel, presaging the potential effects of a failure to secure a last-minute trade deal. “It's a tragedy what's happening in Britain and this Brexit is a tragedy, we see it more and more every day,” said France's EU commissioner Thierry Breton. “If Britain had chosen to remain in the European Union, today we could have helped them.” With days remaining until negotiators are scheduled to head home for Christmas, it remains unclear if the British contingent will have to be airlifted out by RAF aircraft should the Covid-19 blockade remain in place.