Nigel Farage has warned new French Prime Minister and “EU fanatic” Michel Barnier will suit “sell out Starmer”.

President Macron appointed the former Brexit negotiator in a bid to unify French politics.

Known in France as Monsieur Brexit, Mr Barnier will be France’s oldest prime minister since the Fifth Republic came into being in 1958.

He is set to succeed Gabriel Attal, France’s youngest ever prime minister, who President Macron first appointed prime minister in early 2024 and who has stayed in post as caretaker since July.

But Brexiteers warned Mr Barnier’s appointment could spell a new era of relations between Britain and the EU.

Sir Keir Starmer is pushing for a reset in relations with Brussels, insisting he wants closer ties with European capitals.

Reform UK leader and Brexit architect Nigel Farage has blasted: “Michel Barnier becomes the new French Prime Minister. An EU fanatic that will suit sell-out Starmer.”

Senior Tory MP Sir John Hayes told GB News: “We thought we’d seen the last of ‘Monsieur Barnier’ after the Brexit negotiations – where he was determined to get Britain the worst possible deal.”

He called on France to “step up” and work with the UK to stem the tide of illegal migrant crossings in the Channel, urging togetherness to “stop the boats”.

Meanwhile, former Tory leader Iain Duncan Smith said it “shows the desperation of France”.

A statement from Mr Macron’s office announcing Mr Barnier’s appointment said he had been tasked “with forming a unifying government to serve the country and the French people”.

The statement added: “This appointment comes after an unprecedented cycle of consultations during which, in accordance with his constitutional duty, the President ensured that the prime minister and the future government would meet the conditions to be as stable as possible and give themselves the chances of uniting as broadly as possible.”

The appointment of the 73-year-old Barnier follows weeks of intense efforts by Macron and his aides to find a candidate who might be able to build loose groupings of backers in parliament and survive possible attempts by Mr Macron’s opponents to quickly topple the new government that Mr Barnier will now put together and lead.

Mr Barnier has served as French foreign, European affairs, environment and agriculture minister – and twice as a European commissioner – but until now had never had a tilt at any leadership post, like that of president or prime minister.