Stressing that Ukraine "is today protecting Europe", Macron said in Bratislava that it is in the West's interest that Kyiv have security assurances from NATO.

"That is why I'm in favour, and this will be the subject of collective talks in the following weeks... to offer tangible and credible security guarantees to Ukraine," he added.

He said various NATO members could provide these guarantees for the time being as Ukraine waits to join the alliance.

"We have to build something between the security provided to Israel and full-fledged membership," Macron said.

The French head of state is on a visit to Slovakia, where he delivered a speech at an event organised by the international affairs think tank Globsec.

The event, focussed on regional security issues, comes in the run-up to the NATO summit in Lithuanian capital Vilnius on July 11-12.

Macron recalled that he once called the Western defence alliance "brain dead" but said Russia's invasion last year "had jolted NATO awake".

"We need to help Ukraine today with all means to carry out an effective counter-offensive" against Russian forces, Macron said.

"It's what we are currently doing. We have to intensify our efforts because what will happen in the next few months offers a chance even for... a lasting peace."

Macron also called on EU nations to buy European arms and acquire in-depth strike capabilities.

"It is up to us Europeans to in the future have our own ability to defend ourselves," he said.

"A Europe of defence, a European pillar within NATO, is indispensable. It's the only way to be credible... in the long-term," he said.

- 'EU must enlarge' -

The French leader also called for EU enlargement, to bring more countries into the fold.

The European Union should "invent several formats" to meet the membership aspirations of countries in Eastern Europe and the Balkans, he said.

Georgia, Moldova and Ukraine itself are among the countries which have applied to join the European bloc, but conforming to the accession rules can be a difficult and timely procedure.

"Yes, it (the EU) must enlarge. Yes, it must be rethought in terms of its governance and its aims. Yes, it must innovate, no doubt, to invent several formats and clarify the aims of each of these formats," Macron declared.

"This is the only way to meet the legitimate expectations of the Western Balkans, Moldova and Ukraine, which must join the European Union, and to maintain the geopolitical effectiveness, but also the climate, the rule of law and the economic integration of the European Union as it exists today," he insisted.

The two alternatives are to make candidate nations "wait indefinitely" or to let them swiftly join the existing EU structure with the risk that the bloc will no longer be able to function.

Macron will next visit Moldova on Thursday where he will meet with fellow European leaders, including from outside the European Union.