Russia renewed its shelling in the area of Ukraine's Zaporizhzhia nuclear power plant, a local official said Wednesday, a day after the United Nations atomic watchdog agency pressed for the warring sides to carve out a safe zone there to protect against a possible catastrophe.

Meanwhile, Ukrainian forces have attacked the Russian-held eastern town of Balakliia in the Kharkiv region, a senior pro-Moscow separatist official said, as Ukrainian officials remained guarded about how a counteroffensive was faring.

Luhansk region Governor Serhiy Gaidai told Ukrainian television, without giving locations, that a "counter-attack is underway and ... our forces are enjoying some success. Let's leave it at that.

Giving its regular situation report Wednesday morning, Ukraine's military said its ground forces had attacked seven Russian command points and 13 "objects of concentration of Russia's manpower," without saying where.

It also said its forces had repelled Russian assaults on various towns in the eastern Donetsk region, including the strategic city of Bakhmut.

A presidential adviser had tweeted earlier on Tuesday that there would be "great news" coming from the president on the operation in the northeastern Kharkiv region.

In his evening address, however, President Volodymyr Zelenskyy mentioned operations in the Kharkiv region, but he did say five Russian cruise missiles were shot down on Tuesday, most of them in the south.

On the other hand, the city of Nikopol, located on the opposite bank of the Dnieper River from Europe's largest nuclear power plant, was fired on with rockets and heavy artillery, regional governor Valentyn Reznichenko said.

The reports of nearby shelling, which couldn't be independently verified, have caused international alarm. The head of the International Atomic Energy Agency, Rafael Grossi, warned the U.N. Security Council on Tuesday that "something very, very catastrophic could take place" at Zaporizhzhia.

In a detailed report on its visit, the IAEA said shelling around Europe’s largest nuclear power plant should stop immediately. "This requires agreement by all relevant parties to the establishment of a nuclear safety and security protection zone" around the plant, it said.

"There are fires, blackouts and other things at the (plant) that force us to prepare the local population for the consequences of the nuclear danger," Reznichenko said.

The potential peril led the U.N. atomic watchdog agency to urge Russia and Ukraine to establish a "nuclear safety and security protection zone" around the plant.

Russia requests 'explanations'

There are fears the fighting could trigger a catastrophe on the scale of the Chernobyl disaster in 1986. The plant was built during the Soviet era and is one of the 10 biggest in the world.

Neither Moscow nor Kyiv officials would immediately commit to the idea of a safety zone, saying more details of the proposal were needed.

Russian President Vladimir Putin said Wednesday there was "no military equipment" at the plant in southern Ukraine, adding that he "certainly trusts" the IAEA report.

But earlier, Moscow had said it wanted "clarifications" from the IAEA.

Russia has requested "additional explanations" from the IAEA on parts of its report on the Zaporizhzhia nuclear power plant in Ukraine, Foreign Minister Sergei Lavrov was quoted as saying on Wednesday.

Lavrov told the Interfax news agency that Moscow required more information about the IAEA's findings and had sent a request to provide extra information.

"There is a need for additional explanations because there are a number of issues in the report. I will not list them now, but we have requested clarifications from the IAEA Director General," Interfax cited Lavrov as saying.

Meanwhile, Ukraine's nuclear operator said Wednesday it would support the deployment of U.N. peacekeepers at the Russian-occupied nuclear plant.

"One of the ways to create a security zone at the (plant) could be to set up a peacekeeping contingent there and withdraw Russian troops," Energoatom chief Petro Kotyn said in remarks broadcast by Ukrainian TV.

Shellings

The eastern city of Sloviansk came under Russian fire on Wednesday morning, damaging a school and another building, according to the head of the city administration Vadym Lyakh.

Firefighters in the city dug deep into the still-smoldering rubble of an apartment building and removed at least one body bag.

Chunks of bricks, debris and concrete lay among the torn branches of nearby trees, mixed with broken glass and roof tiles. Metal doors, buckled by the force of the blast, hung off their hinges.

Three civilians were killed in Russian shelling in the Donetsk region, the Ukrainian presidential office said. Kharkiv city was hit by rockets twice during the night.

But Ukrainian forces have taken control of an unspecified number of towns in the Kherson region, according to Nataliya Humenyuk, a spokesperson for the southern military command. She said details would come later from the military leadership.

The U.K. defense ministry said there had been heavy fighting on three fronts: in the north, near Kharkiv; in the east, in the Donbass; and in the south, in Kherson Oblast.

Amid a Ukrainian counterattack in the east, "multiple concurrent threats spread across 500 kilometers (310 miles) will test Russia's ability to coordinate operational design and reallocate resources across multiple groupings of forces," the ministry said Wednesday.

The Russian military held large-scale military drills that began last week and ended Wednesday in the country's east that involved forces from China. It was seen as another show of increasingly close ties between Moscow and Beijing amid tensions with the West over the military action in Ukraine.