French President Emmanuel Macron on Thursday met leaders of the country's main political parties as he sought to hammer home the importance of greater support for Ukraine ahead of European elections this summer.

Last week Macron stunned many in Europe by refusing to rule out the dispatch of Western ground troops to Ukraine, pointing to Russia's hardening stance.

Although members of the opposition denounced his remarks, Macron has since doubled down on his calls to ramp up military aid for Ukraine, which is struggling on the battlefield two years into Russia's invasion.

The president and party leaders were expected to discuss the war, including the results of an international conference to step up military support for Ukraine held in Paris last week.

France's parliament will have a chance to vote on the country's Ukraine strategy, including a bilateral security treaty signed with Kyiv last month, after debates in the National Assembly lower house next Tuesday and the Senate upper house on Wednesday.

Ahead of meeting the opposition, Macron had spoken to his predecessors Francois Hollande and Nicolas Sarkozy at the Elysee Palace late Wednesday.

Speaking to journalists after the talks, Hollande called for more aid for Ukraine as well as European unity.

"The only possible response is to show that we are with the Ukrainians in total solidarity, that we are giving them all the support they need, without taking part in any combat ourselves," Hollande said.

Asked about the possibility of sending troops, the Socialist former president said: "My position on military issues is: the less we say, the better."

- Far-right criticised -

On Wednesday, government spokeswoman Prisca Thevenot said that it was "quite obvious" that the far-right National Rally (RN) was not aligned with Macron's call to do everything to ensure Russia's defeat.

Prime Minister Gabriel Attal has accused the RN of "supporting Russia more than Ukraine".

The National Rally (RN) is the largest opposition party in France's lower house of parliament and leads Macron's alliance by a wide margin in European election polls.

Most of Macron's European allies said they would not send troops to Ukraine, while French officials also insisted any such forces could be sent to back operations such as de-mining rather than fighting Russian forces.

In an apparent response to Macron, Russian President Vladimir Putin has warned of a "real" risk of nuclear war and said "that we also have weapons that can hit targets on their territory."