The U.K. has been plunged into Christmas chaos with police blocking people from boarding packed trains, holidays abroad scrapped and travel with Europe banned after London went into an emergency lockdown.

France on Sunday suspended inbound travel from the U.K. for 48 hours and Germany halted arriving flights from Britain, which is in the middle of delicate Brexit negotiations with its European Union partners. Those talks are still at a critical stage after the weekend.

In a sudden turnaround, Prime Minister Boris Johnson canceled plans to allow families to see each other over the festive period as the government warned that a new strain of the coronavirus is "out of control.” There were scenes of panic at train stations, with people defying social-distancing rules to get out of the capital before the new rules took effect on Sunday.