The "risks associated with the epidemic, whose peak has not passed yet, are extremely high," Putin said. "This does not give me the right to begin preparations for the parade and other mass events now."

He said the event would be held later in 2020.

Russia commemorates the Soviet Union's victory over the Nazis each year on May 9 with a massive military display that sees thousands of troops and tanks parade through Red Square and military jets fly in formation over the capital.

This year's parade was meant to be a major showcase for Putin, with world leaders and veterans from all over Russia invited to watch and take part in events over four days.

Moscow had stopped short of postponing the parade as the number of coronavirus infections across the country grew, but the ambitious plans had seemed increasingly unrealistic in recent weeks.

The number of Russian coronavirus cases has been accelerating, with a new record increase of 3,448 infections reported Thursday.

There have been 27,938 cases of infections and 232 deaths, according to official figures, but the real number is believed to be higher.

Thursday's decision came a day after veterans groups urged the Kremlin to call off the event over concerns for health and safety.

A letter signed by the heads of three veterans' organisations urged Putin to "take a difficult but, as we see it, fair decision to hold the military parade on another date".

The letter called on the Kremlin to hold the celebrations at a time when the parade would "not to be a threat, but a real celebration of peace and security for all its participants".

- Fear of 'new wave' of cases -

The organiser of a mass event on May 9 called the Immortal Regiment -- in which marchers carry portraits of relatives who died in WWII -- also asked participants to stay at home this year over coronavirus fears.

Sergei Lapenkov told the Echo of Moscow radio station that if thousands of people gathered in the streets it "could provoke a new wave of illnesses".

Before the pandemic, world leaders including France's Emmanuel Macron were expected to attend the military parade that was set to last 90 minutes and include 15,000 troops and the latest missile systems.

In early March, the United States told the Kremlin that US President Donald Trump would not be attending.

It was unclear whether other cities throughout Russia planned to go head with their own WWII anniversary celebrations.

Alexander Lukashenko, the strongman leader of neighbouring Belarus, has vowed that his country will go ahead as planned and state media on Thursday aired footage of rows of tanks rehearsing.

Ex-Soviet Moldova on Wednesday announced it was postponing its May 9 events.

The coronavirus pandemic had already thwarted a critical political event for Putin.

Russians were due on April 22 to vote on landmark constitutional reforms introduced by the president, which would have paved the way for Putin to potentially stay in power until 2036.

Critics had described the reforms, which included a last-minute amendment to reset presidential terms, as a pretext to allow Putin to become "president for life".