The French president, Emmanuel Macron, has described European nationalists as “hidden Brexiteers” selling the public the “same lies” as those who campaigned for Britain to leave the European Union.

In an interview with the Economist, Macron said the only way to stop the rise of nationalism was by “being bold enough not to think that their rise is inevitable”.

And he reiterated that he did not rule out sending French troops to Ukraine if Russia broke through frontlines and Kyiv requested soldiers.

Macron gave the interview after a speech last week in which he declared that Europe was “mortal … and could die” in part because of the existential threat posed by Russian aggression following Moscow’s invasion of Ukraine in February 2022.

He was speaking weeks before European elections in June in which the far-right Rassemblement National (RN) is expected to win with a crushing majority against Macron’s centrist Renaissance party. It is not alone: across the 27-member bloc, most polls predict the biggest gains for the far-right Identity and Democracy (ID) group in the European parliament, which includes Germany’s Alternative für Deutschland (AfD) and Italy’s Lega.

“What kills me, in France as in Europe, is the spirit of defeat. The spirit of defeat means two things: you get used to it and you stop fighting,” said Macron.

“The second is “what’s-the-pointism”, cowardice. People look at the polls, but polls don’t make politics. It’s your ability to get things done that does. And so everyone says that nationalism is on the rise. Obviously, that’s simpler. But nationalists are distorting the European debate.”

Pointing to the effect of Britain’s decision to leave the EU, he added: “Brexit has impoverished the United Kingdom. Brexit has done nothing to solve immigration in the UK. Well, despite that, some people think it doesn’t look so bad, but nobody dares to say that anything is wrong. And so nobody is taking responsibility for anything.”

Returning to nationalist parties in the EU, he said: “In a way it’s as if we were saying it’s not a problem if we entrust the bank to robbers. When they are around the table, they take Europe hostage.

“So I say to Europeans: Wake up. Wake up! They are hidden Brexiteers. All European nationalists are hidden Brexiteers. It’s all the same lies. In the end, it’s the same results. And make no mistake. If you entrust the keys to people who think like they do, there is no reason why Europe should become a great power. No reason at all.”

He pointed out the RN had wanted to pull out of Europe and the euro, “out of everything”. “Now it no longer says anything. It’s reaping the benefits of Europe, while wanting to destroy it without saying anything.

“And that’s true in every country,” he added.

On Ukraine the French president – who in February made a stir when he first refused to rule out sending ground troops – said again that he was “not ruling anything out because we are facing someone [Putin] who is not ruling anything out” and described Russia as “a power of regional destabilisation … a threat to European security”.

He said the question of sending French troops to Ukraine would “legitimately” arise if Russia broke through Ukrainian lines, and he was issuing a “strategic wake-up call” to European counterparts.

“If Russia decided to go further, we will in any case all have to ask ourselves this question.

“I have a clear strategic objective: Russia cannot win in Ukraine. If Russia wins in Ukraine, there will be no security in Europe,” he said.

“Who can pretend that Russia will stop there? What security will there be for the other neighbouring countries, Moldova, Romania, Poland, Lithuania and the others?”