Expectations for the talks -- initially proposed by Putin -- sank after the Russian leader declined Ukrainian President Volodymyr Zelensky's call to meet at the presidential level in Turkey.

"He knows extremely well that the ball is in his court, that he is in trouble, that he made a big mistake by sending this low-level delegation," Rutte told reporters in Tirana, at a meeting of European leaders who were expected to close ranks around Zelensky.

"I think all the pressure is now on Putin," said Rutte. "The ball is clearly in his part of the field now, in his court," said Rutte. "He has to play ball. He has to be serious about wanting peace."

Leaders were set to seek ways to further ramp up pressure on Moscow at Friday's meeting of the European Political Community (EPC) in Albania, bringing together the members of the European Union and some 20 other countries.

Zelensky was to address the gathering's opening session, taking place as talks get underway between the warring sides in Turkey.

Russia's delegation in Istanbul is being led by Vladimir Medinsky, a hawkish adviser to Putin who has questioned Ukraine's right to exist and led failed talks in 2022 at the start of the war.

Ukraine's side is headed by Defence Minister Rustem Umerov, who is from the Crimea peninsula that Russia annexed in 2014, along with about a dozen deputy-level officials.