French President Emmanuel Macron said on Monday he would not rule out the delivery of fighter planes to Ukraine but warned against the risk of escalation in the conflict.

"Nothing is excluded in principle," Macron said after talks with Dutch Prime Minister Mark Rutte when asked about the possibility of sending jets to Kyiv as it battles Russia's invasion.

But Macron set out a series of "criteria" before making any decision, as Ukraine steps up calls for more advanced weapons from the West just days after its allies pledged to deliver tanks.

These included that Ukraine must first make the request, that any arms would "not be escalatory" and that they would "not be likely to hit Russian soil but purely to aid the resistance effort".

Macron added that any arms delivery "must not weaken the capacity of the French armed forces."

The French president added that the Ukrainians "are not making this request at the moment for fighter jets."

Dutch politicians have recently floated the idea of sending F-16 jets to Ukraine but Rutte echoed Macron's cautious comments.

"There is no taboo but it would be a big step," said the Dutch premier.

"It is not at all a question of F-16s, there has been no demand (from Ukraine)."

The French and Dutch leaders made their comments a day after German Chancellor Olaf Scholz said he would not send fighter jets to Ukraine.

Scholz only just agreed on Wednesday to send 14 Leopard 2 tanks to Ukraine and to allow other European countries to send theirs, after weeks of intense debate and mounting pressure from allies.

Scholz's decision to green-light the tanks was accompanied by a US announcement that it would send 31 of its Abrams tanks.

Ukrainian President Volodymyr Zelensky said last week however that he wants the West to send long-range missiles and jets to help his country repel Russian troops.