The European Commission is planning to demand the EU's 27 remaining member states increase their preparations for a "no deal Brexit" on the very day that Britain new chief negotiator visits Brussels for the first time in his new role.

A 15 page document of strongly worded advice urging the EU-27 to boost their Brexit contingency plans will go in front of the weekly “college of commissioners” meeting in Brussels on Wednesday. The commission is leading Brexit negotiations on the EU-27’s behalf.

If approved, EU sources said it is set to be circulated among national governments and published on Thursday, which will be the first day that Dominic Raab, the new Brexit Secretary, meets Michel Barnier, the European Union’s chief Brexit negotiator.

The document risks embarrassing Mr Raab, who replaces David Davis after his resignation, because it warns of long queues at ports and aviation chaos.

Other warnings paint a dire picture of the consequences for the customs, animal, health, pharmaceuticals and financial services sectors, in particular those in the City of London, which will lose access to the Single Market.