The chief of staff, Andriy Yermak, was addressing an international meeting devoted to implementing a peace plan, one of several gatherings staged as a follow-up to last June's world "peace summit" hosted by Switzerland.

"Don't expect this war to end when the warring sides begin to talk to each other," Yermak told the gathering, according to the president's website. "Don't be deceived. This war will end when the last soldier of the occupying army returns home."

The gathering was attended in person in Kyiv and online by representatives of 56 countries and organisations.

Yermak told the meeting that concerted international pressure on Russia should set a precedent.

"This will prove to the entire world that the pursuit of international conquests in the 21st century is immoral and senseless. Whatever has been seized will have to be returned to the rightful owners," he was quoted as saying.

The international community, he said, had to prove stronger than any aggressor, "however strong that aggressor might be".

The conference has been devoted to the points of Zelenskiy's "peace formula" first presented in late 2022, which also include restoration of Ukraine's 1991 post-Soviet borders and a means to bring Russia to account for its invasion.

In his nightly video address, Zelenskiy restated his determination to hold a second summit to help bring a "just end" to the war. He has called for a meeting to be held by the end of 2024.

Russia, uninvited to the June summit, has said it will attend no similar meetings, though Zelenskiy has said he wants Moscow to be present at the next gathering.

Russian President Vladimir Putin, speaking prior to the June summit, said Russia was willing to hold talks but Ukraine must first recognise as Moscow's territory the four Ukrainian regions it annexed months after the February 2022 invasion.

Moscow has since ruled out any talks while Ukrainian troops remain in Russia's southern Kursk region, where it launched an incursion in August.