All of Ukraine's nuclear power plants and the majority of its hydroelectric and thermal power plants were temporarily off the grid on Wednesday after they were rendered de-energized, the country's energy ministry said.

"Today's missile attack has led to a temporary blackout of all nuclear power plants and most thermal power plants and hydroelectric power plants," the ministry said.

Kiev currently pic.twitter.com/fXbM6OqO7c

— AZ 🛰🌏🌍🌎 (@AZgeopolitics) November 23, 2022

Reportedly, the South Ukraine Nuclear Plant in Mykolaiv Region was reported to have switched into emergency mode first. Later, the same was reported for Rivne and Khmelnytsky nuclear plants in the country's west. This was attributed to the Ukrainian side's failure to supply its substations, leading to a decrease in power consumption.

Eventually, all of the Ukrainian nuclear power plants were off the grid after the authorities took them off the energy system, and it was not known whether engineers would be assembling energy circuits and reactivating some of the nuclear power plants.

Internet connectivity in the various oblasts. Tweeting activity from Ukraine may be light today. pic.twitter.com/4XMLKTCGZa

— Big Serge ☦️🇺🇸🇷🇺 (@witte_sergei) November 23, 2022

However, the vast majority of electricity consumers throughout the country were de-energized, the government said. It noted that emergency shutdowns occur and stressed interrupting in heating and water supply due to a power outage.

This comes days after an adviser to the head of Rosenergoatom, a subsidiary of Russian state nuclear energy corporation Rosatom, said that further Ukrainian shelling of the Zaporozhye Nuclear Power Plant may lead to a real nuclear disaster.

"A nuclear disaster could take place. A nuclear reactor is working, its power supply stops because of the shelling... How could a reactor be cooled down? Not cooling it down could lead to the reactor's overheating, and then it could result in a disaster," Renat Karchaa, an advisor to Rosenergoatom's CEO, told Russian broadcaster Channel One.

🇷🇺🇺🇦⚛️💡Еmergency shutdown of Ukrainian nuclear power plants

First, the South Ukraine Nuclear Plant in Mykolaiv Region was reported to have switched into emergency mode. Later, the same was reported for Rivne and Khmelnytsky nuclear plants in western Ukraine. pic.twitter.com/N8MVwnX3RK

— Rybar in English (@rybar_en) November 23, 2022

On Sunday, the Russian Defense Ministry said that Ukrainian troops subjected the Zaporozhye NPP to massive artillery shelling, damaging strategic facilities by conducting strikes with 155-caliber NATO ammunition in the first mass shelling since late September.

A team of experts from the International Atomic Energy Agency (IAEA) examined the damage and, while confirming its "widespread" scale, said that they had found no immediate nuclear safety threats. However, IAEA head Rafael Grossi said he had "intensified consultations" on the creation of a protection zone around the plant.

IAEA experts found widespread damage done to the territory of the ZNPP, the agency announced on Monday in a statement after four IAEA nuclear safety, security, and safeguards experts visited the ZNPP.

The four-man team carried out the visit to the ZNPP after heavy shelling hit the facility over the weekend, the UN nuclear watchdog announced, noting that the personnel at the ZNPP have already started repair works.

"The status of the six reactor units is stable, and the integrity of the spent fuel, the fresh fuel, and the low, medium, and high-level radioactive waste in their respective storage facilities was confirmed," the statement added.

Ukrainian troops have shelled the ZNPP with massive artillery shelling, damaging strategic facilities, the same advisor said.