French President Emmanuel Macron has invited his European counterparts to the Elysee palace for a working meeting announced at short notice because of what his advisers say is an escalation in Russian aggression over the past few weeks.

"We want to send Putin a very clear message, that he won't win in Ukraine," a presidential adviser told reporters in a briefing. "Our goal is to crush this idea he wants us to believe that he would be somehow winning."

After initial successes in pushing back the Russian army, Ukraine has suffered setbacks on eastern battlefields, with its generals complaining of shortages of arms and soldiers.

German Chancellor Olaf Scholz, British foreign minister David Cameron, Spanish Prime Minister Pedro Sanchez, Dutch Prime Minister Mark Rutte, as well as leaders from Scandinavian and Baltic countries, are scheduled to attend the conference.

The United States will be represented by Assistant Secretary of State for European and Eurasian Affairs Jim O'Brien and Canada by Defence Minister Bill Blair.

Ukrainian President Volodymr Zelenskiy will address the meeting.

French officials said the security conference in Munich earlier this month, which coincided with the death of Putin's most formidable domestic opponent, Alexei Navalny, was all about "doom and gloom", and that Macron, who is due in Kyiv in March, was keen to dispel that.

"We're neither doomy nor gloomy," the French adviser said. "We want Russia to understand that. Russia will have to count on us all collectively to end this war and restore Ukraine's rights."

French officials have said Russia has shown renewed aggression in recent weeks, including as Putin's flight on a nuclear-capable bomber, in what they view as an attempt to intimidate Europeans at a time U.S. support is thrown into doubt by the presidential election.

The adviser said the working meeting will not be an occasion to announce new weapon deliveries to Ukraine but more to brainstorm ways to be more efficient on the ground, as well as increase coordination between allies and Ukraine.

One area where there could be progress is on the issue of buying hundreds of thousands of ammunition rounds from third countries, something that France has been cautious about as it wants to prioritise the development of Europe's own industry.

"We must be able to deliver more shells. The principle is that shells will be purchased where they are available," said the adviser. "There is no dogmatic (French) position."

Ammunition supplies have become a critical issue for Kyiv. The European Union, though, is falling short of its target of sending Ukraine a million rounds of artillery shells by March, and Czech President Petr Pavel is pushing an initiative of sourcing ammunition from other countries to get urgent aid to Ukraine's military.

(Reporting by Michel Rose; additional reporting by John Irish; Editing by Andrew Cawthorne and Nick Macfie)

By Michel Rose