The European Union has hit back at Boris Johnson’s disparaging claims about the actions of negotiators in Brussels during talks over a post-Brexit free trade agreement, pointing to a long track record of international treaties that were concluded in “perfectly good faith”.

Mr Johnson’s remarks came ahead of a warning from the EU trade commissioner that Britain must comply with the Withdrawal Agreement if it is to secure a free trade deal with Brussels.

The prime minister said his proposed breach of international law is a matter of “ring-fencing” the Brexit deal to stop EU negotiators making “abusive or extreme interpretations” of the provisions of the Withdrawal Agreement.

Meanwhile, presidential candidate Joe Biden issued a warning to the UK government that any future trade deal with the US is “contingent” on respecting the terms of the Good Friday Agreement preventing a hard border on the island of Ireland.