Sadiq Khan has urged French voters to defeat the “narrow populism” of Marine Le Pen in today’s presidential run-off.

The London Mayor met with Ms Le Pen’s rival, Emmanuel Macron, at the end of March and said he hoped the centrist triumphed in the race to become the next inhabitant of the Élysée Palace.

Speaking exclusively to The Independent, Mr Khan said: “I had the pleasure of meeting Emmanuel Macron three or four weeks ago and was really impressed by him – really impressed by how he is putting aside tribalism to try to provide a progressive alternative to what France has seen before.

“As far as I’m concerned the choice couldn’t be clearer: a progressive European who understands the importance of pluralism, diversity, the contribution made by all communities, the benefits of working together, versus the alternative of Marine Le Pen.

“We’ve seen across Europe and across the world the rise of narrow populist parties and nationalism and I think what we need to recognise is there are far more progressive [alternatives] and if they are ably led then people will unite behind that candidate.

“I’m looking forward to Macron defeating the narrow populism of Marine Le Pen.”

The Mayor of London was speaking in London after launching the re-election campaign of Tulip Siddiq, the last Labour MP for Hampstead and Kilburn, who is facing a strong challenge from the Conservatives.

French Presidential Election Show all 20 1 /20 French Presidential Election French Presidential Election Voters line up to cast their ballots REUTERS French Presidential Election French expats queue along the street outside the Lycee Francais Charles de Gaulle to cast their vote in a polling station inside the school, in the first round of the 2017 French presidential election, in London, Britain April 23, 2017. REUTERS/Luke MacGregor - RTS13JM5 REUTERS French Presidential Election People line up to vote in the first round of 2017 French presidential election at a polling station in Vaulx-en-Velin near Lyon, France, April 23, 2017. REUTERS/Emmanuel Foudrot - RTS13HSP REUTERS French Presidential Election Police patrol polling stations in France REUTERS French Presidential Election Francois Fillon (L), member of the Republicans political party and 2017 French presidential election candidate of the French centre-right, casts his vote in the first round of 2017 French presidential election in Paris, France, April 23, 2017. REUTERS/Christophe Archambault/Pool - RTS13IH0 REUTERS French Presidential Election Benoit Hamon (C), French Socialist party 2017 presidential candidate, is surrounded by photographers as he leaves a polling station after voting in the first round of 2017 French presidential election in Trappes, near Paris, France, April 23, 2017. REUTERS/Vincent Kessler - RTS13I0Y REUTERS French Presidential Election French President Francois Hollande collects voting slips before casting his ballot in the first round of the 2017 French presidential election at a polling station in Tulle, France, on April 23, 2017. REUTERS/Georges Gobet/Pool - RTS13ITO REUTERS French Presidential Election A policeman walks by election posters near a polling station during the first round of 2017 French presidential election in Paris, France, April 23, 2017. REUTERS/Christian Hartmann - RTS13I3A REUTERS French Presidential Election Emmanuel Macron and wife Brigitte Trogneux REUTERS French Presidential Election Emmanuel Macron casts his ballot REUTERS French Presidential Election Emmanuel Macron, head of the political movement En Marche !, or Onwards !, and candidate for the 2017 French presidential election, waves hand during in the first round of 2017 French presidential election at a polling station in Le Touquet, northern France, April 23, 2017. REUTERS/Benoit Tessier - RTS13ICH SAA/ French Presidential Election Jean-Luc Melenchon, candidate of the French far-left Parti de Gauche and candidate for the French 2017 presidential election, leaves a polling booth in the first round of 2017 French presidential election at a polling station in Paris, France, April 23, 2017. REUTERS/Stephane Mahe - RTS13IKB REUTERS French Presidential Election Front National leader Marine Le Pen casts her ballot Marine Le Pen (L), French National Front (FN) political party leader and candidate for French 2017 presidential election, casts her ballot in the first round of 2017 French presidential election at a polling station in Henin-Beaumont, northern France, April 23, 2017. At R, Mayor of Henin-Beaumont Steeve Briois. REUTERS/Charles Platiau - RTS13IEI REUTERS French Presidential Election Early ballots are read as results continue to come in Reuters French Presidential Election Macron supporters react as results come in early in the evening AP French Presidential Election Supporters of Front National leader Marine Le Pen cheer as early results come in Reuters French Presidential Election Alamy Live News. J21KYW Paris, France. 23rd April 2017. Marcon supporters wave French and EU flags after the announcement that he is the leader in the exit polls after the polling stations have been closed. Supporters of Emmanuel Macron, the Presidential candidate from the social liberal political party En Marche! celebrate the exit polls, that see him in first place, ahead of Marine Le Pen from the Front National in the first round of the French Presidential election. Credit: Michael Debets/Alamy Live News This is an Alamy Live News image and may not be part of your current Alamy deal . If you are unsure, please contact our sales team to check. Alamy French Presidential Election Front National leader Marine Le Pen takes to the stage to address her supporters as fans cheer Reuters French Presidential Election Emmanuel Macron greets supporters on Sunday night AP French Presidential Election Emmanuel Macron and wife Brigitte Trogneux celebrate the incoming results EPA

After meeting Mr Macron in March, Mr Khan said the 39-year-old had a “progressive, positive vision for France and Europe” but has, until now, stopped short of officially endorsing him.

It comes as French voters head to the polls to choose their next president. Opinion polls suggest Mr Macron is comfortably ahead but there are fears Ms Le Pen could benefit from abstentions and a refusal by some supporters of left-wing Jean-Luc Mélenchon, who was defeated in the first round of voting, to switch their backing to Mr Macron.

The centrist emerged from relative obscurity to stand on the verge of becoming the successor to Francois Hollande, the current president.

Mr Macron only established his En Marche! party last year after leaving the French Socialist Party, in which he served as an economic adviser and member of Mr Hollande’s cabinet.

He led a competitive field during the first round of voting, which saw left-wingers Mr Mélenchon and Benoit Hamon fall by the wayside along with Republican candidate Francois Fillion, a former prime minister of France.