KYIV (REUTERS) -  United Nations (UN) Secretary-General Antonio Guterres called on Monday (Aug 8) for international inspectors to be given access to the Zaporizhzhia nuclear plant after Ukraine and Russia traded accusations over the shelling of Europe’s largest atomic plant at the weekend.

“Any attack on a nuclear plant is a suicidal thing,” Mr Guterres told a news conference in Japan, where he attended the Hiroshima Peace Memorial Ceremony on Saturday to commemorate the 77th anniversary of the world’s first atomic bombing.

Ukraine said renewed Russian shelling on Saturday had damaged three radiation sensors and hurt a worker at the Zaporizhzhia power plant, the second hit in consecutive days on the site.

Ukrainian President Volodymyr Zelensky accused Russia of waging “nuclear terror” that warrants more international sanctions, this time on Moscow’s nuclear sector.

“There is no such nation in the world that could feel safe when a terrorist state fires at a nuclear plant,” Mr Zelensky said in a televised address on Sunday.

Russian forces captured the plant in south-eastern Ukraine in early March but it is still run by Ukrainian technicians.

The Russian-installed authority of the area said it was Ukraine that hit the site with a multiple rocket launcher, damaging administrative buildings and an area near a storage facility.

The Russian embassy in Washington also released a statement itemising the damage.

“Ukrainian nationalists launched an artillery strike on the territory of the specified object on Aug 5.

"Two high-voltage power lines and a water pipeline were damaged as a result of the shelling.

"Only thanks to the effective and timely actions of the Russian military in covering the nuclear power facility, its critical infrastructure was not affected,” the embassy said.

Reuters could not verify either side's version.

Events at the Zaporizhzhia site – where Kyiv alleged that Russia hit a power line last Friday – have alarmed the world.

Mr Guterres said the International Atomic Energy Agency (IAEA) needs access to the plant.

“We fully support the IAEA in all their efforts in relation to create the conditions of stabilisation of the plant,” Mr Guterres said.

IAEA chief Rafael Mariano Grossi warned on Saturday that the latest attack “underlines the very real risk of a nuclear disaster”.

Grain exports pick up steam

Elsewhere, a deal to unblock Ukraine's food exports and ease global shortages gathered pace as two grain ships sailed out of Ukrainian Black Sea ports on Monday, raising the total to 12 since the first vessel left a week ago.

Four ships that left Ukraine on Sunday are expected to anchor near Istanbul on Monday evening, Turkey's defence ministry said, and would be inspected on Tuesday.

The first vessel to sail since Russia's Feb 24 invasion has docked.

The two latest outgoing ships were carrying almost 59,000 tonnes of corn and soybeans and were bound for Italy and south-eastern Turkey following inspections.

The four that left on Sunday bore almost 170,000 tonnes of corn and other food.

The July 22 grain export pact brokered by Turkey and the United Nations represents a rare diplomatic triumph as fighting churns on in Ukraine and aims to help ease soaring global food prices arising from the war.

Before Moscow's Feb 24 invasion, Russia and Ukraine together accounted for nearly a third of global wheat exports.

The disruption since then has threatened famine in some parts of the world.

Grinding battle for Donbas

Russia says it is waging a "special military operation" in Ukraine to rid of nationalists and protect Russian-speaking communities. Ukraine and the West describe Russia's actions as an unprovoked imperial-style war to reassert control over a pro-Western neighbour lost when the Soviet Union broke up in 1991.

The conflict has displaced millions, killed thousands of civilians and left cities, towns and villages in ruins.

It has evolved into a war of attrition concentrated in the east and south-east of Ukraine.

Mr Putin's troops are trying to gain full control of the Donbas region of east Ukraine where pro-Moscow separatists seized territory after the Kremlin annexed Crimea to the south in 2014.

“Ukrainian soldiers are firmly holding the defence, inflicting losses on the enemy and are ready for any changes in the operational situation,” Ukraine’s general staff said in an operational update on Monday.

Russian forces stepped up their attacks north and north-west of Russian-held Donetsk city in the Donbas on Sunday, Ukraine's military said.

The Russians attacked Ukrainian positions near the heavily fortified settlements of Piski and Avdiivka, as well as shelling other locations in the Donetsk region, it said.

In addition to tightening its grip over the Donbas, Russia is entrenching its position in southern Ukraine, where it has gathered troops in a bid to prevent a potential counter-offensive near Kherson, Kyiv has said.

Ukraine conducted long-range strikes on Russian troop bases and two key bridges across the Dnipro river overnight, Ukrainian officials said on Monday.

The strikes hit the only two crossings Russia has to the pocket of southern Ukrainian territory it has occupied on the western bank of the vast Dnipro river, said Ms Natalia Humeniuk, spokesperson for Ukraine’s southern military command.

“The results (of the strikes) are rather respectable, hits on the Antonivskyi and Kakhovskyi bridges,” she said on television.

Russia’s Interfax news agency quoted a Russian-appointed official in the south-eastern city of Kherson as saying on Monday Ukrainian forces had again shelled the Antonivskyi bridge there, damaging construction equipment and delaying its reopening.

The bridge has been a key Ukrainian target in recent weeks, with Kyiv using high-precision US-supplied rockets to try to destroy it in possible preparation for a counter-attack.

Ukrainian HIMARS strikes also hit multiple military bases in Ukraine’s Russian-occupied southern city of Melitopol in the early hours, killing troops and destroying hardware, the exiled mayor said.

“According to preliminary estimates, a significant amount of military equipment was destroyed,” Mayor Ivan Fedorov wrote on Telegram.

Ukraine’s defence minister said two weeks ago that 50 Russian ammunition depots had been destroyed by U.S.-supplied HIMARS multiple rocket launchers, which Ukraine started using in June.

Meanwhile, Russians installed in the wake of Moscow's invasion have toyed with the idea of joining Ukraine's occupied territory to Russia.

Last month, a senior pro-Russian official said a referendum on such a move was likely "towards next year".

In his video address, Mr Zelensky said that any "pseudo-referendums" on occupied areas of his country joining Russia would eliminate the possibility of talks between Moscow and its Ukrainian counterparts or their allies.

"They will close for themselves any change of talks with Ukraine and the free world which the Russian side will clearly need at some point," Mr Zelensky said.

Also on Sunday, Ukraine's chief war crimes prosecutor said almost 26,000 suspected war crimes committed since the invasion were being investigated, with 135 people charged, of whom 15 were in custody. Russia denies targeting civilians.

Shelling and missile strikes were reported overnight in the Ukrainian city of Kharkiv and around military sites in the western region of Vinnitsya, among other places, Ukrainian authorities said.

There was no immediate word on casualties.

Beyond Ukraine, a proxy battle played out at the International Chess Federation where former Russian deputy prime minister Arkady Dvorkovich won a second term as president, defeating Ukraine's Andrii Baryshpolets.

And after days of controversy, Amnesty International apologised for "distress and anger" caused by a report accusing Ukraine of endangering civilians. That had infuriated Mr Zelensky and prompted the head of the rights group's Ukraine office to resign.