European Commission head Jean-Claude Juncker sharply criticised politicians Nigel Farage and Boris Johnson as the "sad heroes" of Brexit who resigned instead of leading Britain through the EU exit they campaigned for.

"I would just note that the proud Brexit heros of last week are now the sad heroes of Brexit," Juncker told a session of the European Parliament in Strasbourg, France.

"Johnson, Farage, they are retro patriots. Patriots don’t resign when things get difficult, they stay," he added.