French President Emmanuel Macron met Ukrainian filmmaker Oleg Sentsov on Tuesday, less than a month after his release from five years in prison in Russia on charges which sparked international outrage.

Sentsov was freed when Russia and Ukraine carried out a long-awaited swap of 35 prisoners each on September 7.

Macron hailed the move, while Sentsov in turn thanked France "for the constant support given for his release" during his five years in jail, a French presidential official said.

The French leader is spearheading a drive to end a conflict which has seen pro-Moscow separatists declare unrecognised breakaway statelets in two Ukrainian eastern regions and left more than 13,000 dead.

The war broke out after Russia's 2014 annexation of the Ukrainian peninsula of Crimea plunged western relations with Moscow into the deep freeze.

President Macron held extensive talks with Putin ahead of hosting the G7 summit in Biarritz in August and said there that he wanted to bring together Putin, Ukrainian President Volodymyr Zelensky and German Chancellor Angela Merkel for peace talks in September.

But in a sign of the challenges of reconciling the positions of Moscow and Kiev the meeting has yet to materialise.

In a speech later to the Parliamentary Assembly of the Council of Europe, Macron said the summit would take place "in the next weeks" and could reach "new stages" in solving the conflict.

He insisted talks had to be based on the Minsk accords, which Germany and France helped to negotiate but which failed to stop the fighting in eastern Ukraine.

Criticised by some for being too close to Putin, Macron insists that despite insisting on negotiations, "we are not naive, we are not complacent and we are aware that red lines have been crossed" by Russia in its actions in Ukraine.

Macron held brief talks with Putin in Paris after the funeral on Monday of former French president Jacques Chirac but no details were disclosed.

Sentsov was arrested in 2014 and was serving a 20-year sentence in a Russian Arctic penal colony for planning "terrorist attacks" in Moscow-annexed Crimea. The filmmaker, who lived in Crimea before his arrest, said he would make Kiev his new home.

Germany Russia Ukraine Putin