Ukraine has agreed to hold talks with Russia on the Belarus border, news agency AFP reported on Sunday, quoting the presidency, shortly after Valdimir Putin ordered his defence chiefs to put the country's nuclear "deterrence forces" on high alert.

"I order the Defence Minister and the Chief of the General Staff of the Russian Armed Forces to put the deterrence forces of the Russian army into a special mode of combat service," Russian President Vladimir Putin said, accusing the West of taking "unfriendly" steps against his country.

Almost around the same time, Ukraine announced it was ready to hold talks with Russia at its border with Belarus - near the Chernobyl exclusion zone - after a phone call between President Volodymyr Zelensky and Belarusian leader Alexander Lukashenko.

Ukraine had earlier turned down Moscow's offer of a meeting in Belarus, which has allowed Russian troops passage to attack Ukraine. Ukraine had proposed Warsaw, Bratislava, Budapest, Istanbul and Baku as possible alternative locations for any talks.