Boris Johnson described Brexit as “a mess” during a private meeting with senior German officials, European Union sources have claimed.

Mr Johnson is understood to have been referring to the complex Brexit negotiations rather than the British decision to leave the bloc, which he campaigned for in the referendum.

During unminuted talks in Berlin, the Foreign Secretary is alleged by Brussels sources to have urged the Germans to turn Brexit into an economic opportunity.

However, The Telegraph understands he was rebuffed by the German government, which has repeatedly stood behind Michel Barnier and resisted any attempts to go over the European Union chief Brexit negotiator's head.

The claims were furiously denied on Tuesday night by friends of Mr Johnson, who branded them a smear and a hatchet job.

A friend of Mr Johnson said: "These old claims will be rightly dismissed as nonsense by anyone sensible. Boris knows Brexit will be a great success and is committed to taking back control of our money, laws and borders."