Downing Street congratulated Brexit negotiator Michel Barnier on his appointment as French prime minister as Sir Keir Starmer continues efforts to reset the UK’s relationship with the European Union.

Mr Barnier led the EU team during the Brexit wrangles that resulted in the Trade and Co-operation Agreement (TCA).

Asked for Sir Keir’s response to Mr Barnier’s appointment, a Downing Street spokeswoman said: “We wish him all the best in his new role. The UK enjoys a strong relationship with France.

“The PM visited Paris just last week, and we are committed to working collaboratively on our shared priorities, from tackling illegal migration to supporting Ukraine and delivering sustainable economic growth.”

She added: “We want to reset our relations with the EU and make Brexit work better for British people. And we are also resetting our relations with European countries at a bilateral level.”

Reform UK leader Nigel Farage was scathing about Mr Barnier’s appointment, describing him as “an EU fanatic that will suit sell-out Starmer”.

Sir Keir was shadow Brexit secretary through the bitter divorce proceedings between the UK and Brussels and impressed Mr Barnier.

“I get the feeling that Keir Starmer will one day be UK prime minister,” he wrote in a 2018 diary entry.

The appointment of the veteran Mr Barnier, 73, follows weeks of intense efforts by French President Emmanuel Macron to find a candidate who might be able to hold together a new government following July’s elections.

But left-wing leader Jean-Luc Melenchon immediately came out against his appointment, predicting the new prime minister would not get a majority backing in the deeply split National Assembly.

The July 7 elections left the French parliament’s lower house split between three main blocs — the left, including Mr Melenchon’s party, the centre where Mr Macron has based his support, and the far right, converging around anti-immigration leader Marine Le Pen’s National Rally.