Kiev ( Ukraine ) (AFP) - Ukraine's state nuclear energy corporation Energoatom said Tuesday in a statement that it had suffered an "unprecedented" Russian cyberattack on its website, and that its operations had not been affected.

"On August 16, 2022, the most powerful cyberattack since the beginning of the Russian invasion took place against the official Energoatom website," she wrote on Telegram.

It added that the site "was attacked from Russian territory."

Energoatom said the Russian "people's cyber army" group used more than seven million bots to attack the website over a three-hour period.

Around noon, a channel on Instagram in Russian called "People's Cyber Army" called on its followers to attack the website of the Ukrainian Nuclear Energy Corporation.

But by Tuesday evening, it had announced a "change" of the scheme, redirecting supporters to a new target, the Ukrainian Institute of National Remembrance, and its website had slowed down.

The cyber attack comes at a time of heightened tensions around the Zaporizhia nuclear plant in southern Ukraine, which Russian forces occupied in March shortly after the start of the invasion.

Since the end of July, multiple bombings have targeted the site, and the two sides have exchanged accusations about it. Fears of a nuclear catastrophe were also raised.

Before the Russian invasion, Ukraine relied on four nuclear plants to secure about 50 percent of its electricity needs.

Ukraine witnessed the worst nuclear accident in the world in 1986, when the fourth reactor exploded at the Chernobyl plant, which led to a massive radioactive leak.