Ukrainian President Volodymyr Zelenskyy has refused to host United Nations Secretary-General Antonio Guterres in Kyiv following his visit to Russia, where he was pictured shaking hands with Russian President Vladimir Putin, an official close to Zelenskyy said.

“He shook hands with him [Putin]. He smiled. He was asked to come to promote the BRICS summit even more. He was used by them, and he seemed happy to be used,” the official told POLITICO on condition of anonymity to be able to discuss the sensitive matter.

Guterres went to the city of Kazan, Russia, to attend the BRICS summit, where on the sidelines he met Putin — who is wanted by the International Criminal Court for alleged war crimes. In remarks at the summit, Guterres called for a “just peace.” After his visit to Russia, Guterres planned to travel to Kyiv.

Zelenskyy criticized Guterres in an evening speech on Thursday that marked United Nations Day, in which he said it is “crucial” the world remembers the goals and principles of the U.N. Charter.

“Even if some officials prefer the allure of Kazan over the substance of the U.N. Charter, our world is structured so that the rights of nations and international legal norms matter, and will continue to matter,” said Zelenskyy in his address.

Ukraine’s Foreign Ministry earlier also slammed the U.N. chief for his attendance decisions.

“The UN Secretary General declined Ukraine’s invitation to the first global peace summit in Switzerland. He did, however, accept the invitation to Kazan from war criminal Putin,” Ukraine’s Foreign Ministry posted on X on Monday. “This is a wrong choice that does not advance the cause of peace. It only damages the UN’s reputation,” the post continued.

Not only Ukraine criticized Guterres over his visit.

Guterres’ move garnered various reactions, including from Lithuanian Foreign Minister Gabrielius Landsbergis, who indirectly challenged the U.N. head to step down.