Russia backs the idea of Ukraine meeting but not at Chernobyl. It may cut gas supplies.
Ukraine has four operational nuclear power plants, including Europe's largest by capacity, at Zaporizhzhia near Crimea.
A building close to Zaporizhzhia Plant caught fire last week after what appeared to be a Russian military projectile hit it. Russia blamed Ukrainian saboteurs. Russian forces now control the plant, with Ukrainian staff working under their orders.
The fire was extinguished and the reactors undamaged but the incident highlighted the potentially catastrophic consequences if a nuclear plant were hit.
UN atomic watchdog chief Rafael Grossi proposed the tripartite meeting at Chernobyl with Ukraine on ensuring the safety of nuclear facilities there during Russia's invasion. Russia backs it but not at Chernobyl where Russia has seized a radioactive waste facility near the defunct power plant where the world's worst nuclear accident happened in 1986.
"Russia supported Grossi's idea regarding a trilateral meeting and we expect that the Ukrainians will also be cooperative," Russia's IAEA ambassador Mikhail Ulyanov told reporters on Monday.
"I believe Chernobyl is not the best place for such a meeting. There are numerous capitals in the world."
Ukrainian President Volodymyr Zelensky also backed the idea of a meeting.
The evacuations started after both the Russian and Ukrainian officials agreed to set up humanitarian corridors to allow civilians out of areas seized by the Russian forces.
On Monday, the Ukrainian authorities during the third round of talks with their Russian counterparts had rejected an offer for humanitarian corridors that would lead refugees from the attacked cities into Russia and Belarus.
Russia has said it may close its main gas pipeline to Germany if the West goes ahead with a ban on Russian oil. The US has been exploring a potential ban with allies as a way of punishing Russia for its invasion of Ukraine.
But Germany and the Netherlands rejected the plan on Monday.