Moscow/Kyiv, Aug 28 : Ukraine's state-run energy company Ukrenergo has said that it has implemented nationwide power cuts following Russia's largest-ever airstrike on the country.

Ukrenergo said that electricity restrictions would be in place in all Ukrainian regions from 6 to 11 a.m. local time, and from 3 to 9 p.m. on Tuesday, as more than 500 settlements across Ukraine remain without power, Xinhua news agency reported.

Russia on Monday launched 127 missiles and 109 combat drones, targeting energy infrastructure across Ukraine, Ukrainian Air Force Commander Mykola Oleshchuk said on Telegram, claiming "the most massive air attack".

The Russian Defence Ministry confirmed in a statement on Tuesday that it had carried out a group strike with long-range airborne precision weapons on critical Ukrainian airfield infrastructure, saying "all designated targets were hit".

The efforts to repair damaged power infrastructure are underway, said Ukrenergo.

Russia fired dozens of missiles and drones across Ukraine for a second day on Tuesday, including some that Ukraine's President Volodymyr Zelensky said were shot down by Western-supplied F-16 fighter jets before they reached their targets.

The onslaught killed at least five people, destroying a hotel, homes and residential buildings as well as critical infrastructure in multiple Ukrainian regions. Kyiv and other cities had power outages in sweltering heat.

As it often does in statements after Russian bombing raids, Ukraine's military listed the Russian regions and occupied territories where the weapons were launched. President Zelensky and other top officials have called repeatedly for the US to lift restrictions and let Ukraine strike deep inside Russia to hit military infrastructure responsible for the war.

"(The allies) try not to speak with me about it. But I keep raising this topic. Generally, that's it. The Olympics are over, but the ping-pong continues," the Ukrainian President said.

In comments addressing the apparent first use by Ukraine of the F-16s to shoot down a missile, Zelensky thanked Ukraine's supporters for them but said there were too few, and too few pilots trained to fly them.

Among the Russian regions listed as a source of Tuesday's attack was Kursk, where the head of the Ukrainian army said his troops have gained control of nearly 1,300 square kilometers (500 square miles) since their surprise incursion three weeks ago. That's roughly the size of Los Angeles.

General Oleksandr Syrskyi also said Ukraine had captured 594 Russian prisoners in the operation, which he said was intended to draw Russia's military away from the fighting in Ukraine. His claims could not be independently confirmed.

The Kursk operation, the largest incursion into Russia since World War II, has forced some 130,000 residents to evacuate their homes. Russia has sent reinforcements into the region, but it was not clear to what extent the movements might be weakening Russia's positions in Ukrainian territory.

Fighting in the region has raised concerns about dangers to the Kursk nuclear power plant, said International Atomic Energy Agency chief Rafael Grossi, who visited it on Tuesday. He said in a post on X the situation was "serious" and called any attack on a nuclear plant unacceptable.

"There is now a danger of a nuclear incident here," Grossi said.

"Today I was told about several cases of drone attacks on the territory, on the plant's facilities. At the plant I saw traces of these attacks."

But the plant now is operating "in a mode very close to normal," he added.

The Russian Defence Ministry asserted on Tuesday that Ukraine had suffered heavy casualties in Kursk -- some 6,600 troops killed or injured -- and that more than 70 tanks had been destroyed along with scores of armoured vehicles. Those figures could not be independently confirmed.

The head of the Ukrainian army's claim of territorial control came hours after the second consecutive barrage of nighttime air and missile attacks from Russia.

Five people were reported killed and 16 injured in the attacks, which Zelensky said included 81 drones as well as cruise and ballistic missiles.

In the Kyiv region, which struggled with blackouts after Monday's onslaught that targeted energy facilities throughout the country, five air alerts were called during the night. The regional administration said air defences destroyed all the drones and missiles but falling debris set off forest fires.

After Monday's barrage across Ukraine of more than 100 missiles and a similar number of drones, Ukrainian Prime Minister Denys Shmyhal said "the energy infrastructure has once again become the target of Russian terrorists" and urged Ukraine's allies to provide it with long-range weapons and permission to use them on targets inside Russia.

US President Joe Biden called Monday's Russian attack on energy infrastructure "outrageous" and said he had "reprioritised US air defence exports so they are sent to Ukraine first".

He also said the US was "surging energy equipment to Ukraine to repair its systems and strengthen the resilience of Ukraine's energy grid".

Russian officials reported four Ukrainian missiles were shot down over the Kursk region.

/IANS