Russia on Wednesday urged foreign embassies and international organisations in Kyiv to ensure the "timely evacuation" of their staff and citizens in case of a Russian strike on the city.

In a note to foreign diplomatic missions, Russia warned it would launch a "retaliatory strike" on the Ukrainian capital, "including against decision-making centres", if Ukraine disrupted World War II Victory Day commemorations in Moscow on Saturday.

It urged them to "ensure the timely evacuation of personnel from diplomatic and other missions, as well as citizens, from the city of Kyiv".

Russia did not elaborate on the threat and there was no immediate comment from Ukraine.

Russia marks World War II Victory Day each year on May 9 with a massive military parade through Red Square.

The country earlier this week declared a unilateral ceasefire with Ukraine between May 8 and 9 to coincide with the commemorations.

Ukraine's President Volodymyr Zelensky said Monday that having a ceasefire so Moscow could mark the celebration was "not serious", and that Russia was afraid Ukrainian drones would "buzz over Red Square".

Ukraine declared its own ceasefire for May 6, which Kyiv says Russia has repeatedly violated.