In this photo provided by the IAEA Press Office, U.N. atomic energy chief Rafael Mariano Grossi stands on a road next to a UN vehicle on his way to the Zaporizhzhia Nuclear Power Plant, in southeastern Ukraine, Wednesday March 29, 2023. ( AP)
There are persistent fears about the safety of the nuclear plant -- Europe's largest -- which is located in the southern Zaporizhzhia region where there has been frequent shelling since Russian troops invaded.
Rafael Grossi, head of the International Atomic Energy Agency (IAEA), and his delegation are expected to arrive Wednesday morning and leave by afternoon, according to the Russian news agency TASS, citing an official with Russia's nuclear operator Rosenergoatom.
This will be Grossi's second visit to Zaporizhzhia since Russia invaded Ukraine in February last year, and he plans to "assess first-hand the serious nuclear safety and security situation at the facility", according to the IAEA.
The agency has had a team of experts inside the plant since September 2022, but Grossi said the situation "is still precarious".
Before his visit, he met on Monday with Ukrainian President Volodymyr Zelensky, who said it was not possible to restore safety at the nuclear plant with Russia still in control.
"Without the immediate withdrawal of Russian troops and personnel from the Zaporizhzhia nuclear plant and adjacent territory, any initiatives to restore nuclear safety and security are doomed to failure," Zelensky told Grossi.
The plant needs reliable electricity supply to ensure essential nuclear safety and security functions.
But it has suffered repeated electricity outages during the war, causing alarm in the IAEA and the international community.
The Russian invasion has caused devastation across swathes of the country, and despite more than 13 months of gruelling battles, Ukraine's top diplomat on Tuesday struck a defiant tone.
"Russia has to withdraw from every square meter of Ukrainian territory," Foreign Minister Dmytro Kuleba said in a virtual session ahead of the Summit for Democracy, which US President Joe Biden will formally kick off on Wednesday.
"There should be no misinterpretation of what the word withdrawal implies."
'Crime of aggression'
In Ukraine's eastern Donetsk region, fighting in recent months has been concentrated on the eastern city of Bakhmut, with Kyiv saying it is holding out in the urban hub to exhaust Russian troops.
A key military objective of Russia's invasion is the complete capture of Donetsk, which it already claimed to have annexed last year even as fighting there is ongoing.
Moscow said Tuesday it had for the first time downed a long-range rocket supplied by the United States to Ukraine.
"Air defence (forces) downed... a GLSDB guided rocket," Russia's defence ministry said in a statement, referring to ground-launched small diameter bombs.
These devices have a range of up to 150 kilometres (93 miles), which could threaten Russian positions and supply depots far behind the front lines.
On the legal front, the United States on Tuesday threw its support behind a special international tribunal to try Russia for "aggression" against Ukraine.
The crime of aggression -- also known as a crime against peace -- was last prosecuted against Nazi Germany and Imperial Japan in the aftermath of World War II.
"We envision such a court having significant international support," a US State Department spokesperson said Tuesday.
The European Union has already advocated for such a tribunal, which could bring fresh charges against Russian President Vladimir Putin.
So far, the International Criminal Court has issued an arrest warrant for Putin over the alleged war crime of unlawfully deporting Ukrainian children.
The Kremlin has dismissed the warrant as "void", as Russia does not recognise the jurisdiction of the ICC.
Since the invasion, more than 850 health facilities in Ukraine have been attacked, according to the World Health Organization -- creating a massive gap in health and emergency services.
A Norway- and EU-backed project is conducting medical evacuation flights, carrying Ukraine's war wounded to hospitals across Europe.
Vladyslav Shakhov, who had to leave Ukraine on a medical flight for treatment after he was hit by shrapnel, said he was "not happy about leaving my country".
"I hope they will get me back on my feet quickly so I can get back," the 24-year-old told AFP.