"There are indications that they are doing things we would prefer them not to do," said Emmanuel Bonne during a rare public address Thursday at the Aspen Security Forum in Colorado, which is being broadcast.

When asked what he was referring to, he said it was the delivery of "kind of military equipment".

"As far as we know, they are not delivering massively military capacities to Russia," he added.

A French diplomatic source told AFP that the advisor referred to the "possible deliveries of dual-use technologies", both civilian and military.

The West has urged Beijing not to deliver arms to Russia for its war in Ukraine.

While they have regularly said there is no evidence to that effect, they are concerned about the possibility of Chinese firms delivering technology that could be used by Russians on the battlefield in Ukraine.

Claiming to be neutral in the conflict, China has called for respect for sovereign states, including Ukraine, but has never publicly condemned the military operation carried out in Ukraine by Russian President Vladimir Putin.

"At the point where we are, when the counteroffensive is beginning in the field, when everything is complicated... what we need most is Chinese abstention" from arms deliveries, Bonne said.

"I'd like China to demonstrate that it is a credible partner" in the conflict in Ukraine, he said, stressing that "I don't have the evidence yet."

On the diplomatic front, "I don't believe a second that China will provide a solution for the war in Ukraine," he said.

"For the war to stop we only need Putin to withdraw and Ukraine to basically beat the Russians in the ground."

It will then be necessary to establish "a very solid kind of negotiation framework" including a wide range of partners such as China and India, "who can have an influence and can guarantee a solid peace," Bonne said.