Setting out his programme, Bardella said he was in favour of continuing to provide "logistical support and defence equipment" to Ukraine but added that he would oppose sending French troops or long-range missiles to the war-torn country, calling those moves "very clear red lines."

"This would create the conditions for French interference and escalation in the face of a nuclear power," the 28-year-old told reporters.

France has been one of Ukraine's main Western backers since Russia unleashed its full-scale invasion of its neighbour in February 2022.

In February, President Emmanuel Macron rattled his European partners by saying he would not rule out the possibility of deploying troops to Ukraine -- a move ruled out by Germany and many other allies.

While warning against a showdown with Russia, Bardella said his party would be "extremely vigilant" in the face of Russian attempts to intervene in France's affairs.

"I see Russia as a multidimensional threat to both France and Europe," said Bardella.

He accused Moscow of challenging France's interests "in our historical spheres of influence in Africa, the Black Sea and also in our overseas territories".

Opponents have long pointed to the warm ties that Bardella's extreme-right National Rally (NR) has enjoyed with the Kremlin in the past as well as a massive loan that the NR's previous incarnation, the National Front, received from a Russian bank in 2014, which it has since repaid.

With the war now in its third year, Ukraine is struggling to repel Russian advances and is in desperate need of greater Western military aid.

Macron said in early June he wanted to finalise a coalition of military instructors to train Ukrainian troops and lashed out at what he called a "camp of pacifists" over Ukraine's fight against Russia.