Britain will face nuclear fuel shortages, truck queues at Dover and “serious disruption” to air traffic if Brexit talks fail, the EU’s chief negotiator has warned as he outlined conditions for an “ambitious” UK-EU trade deal.

In a wide-ranging speech ahead of article 50 exit talks, Michel Barnier warned London that it must agree “principles for an orderly withdrawal” before trade talks, including those relating to its financial dues and the rights of four million UK and EU migrants.