The Red Cross worked to register the soldiers as prisoners of war in a step toward ensuring their humane treatment under the Geneva Conventions.
Meanwhile, in the first war crimes trial held by Ukraine, a captured Russian soldier testified that he shot an unarmed Ukrainian civilian in the head on an officer's orders and asked the victim's widow to forgive him. The soldier pleaded guilty earlier in the week, but prosecutors presented the evidence against him in line with Ukrainian law.
In Mariupol, the nearly three-month siege that has turned the strategic port city into a symbol of the war's horrors drew ever closer to an end as the fighters in the last bastion of resistance continued abandoning the Azovstal steel plant on orders from above to save their lives.
The Russian military said a total of 1,730 Ukrainian troops at the steelworks have surrendered since Monday. At least some were taken by the Russians to a former penal colony in territory controlled by Moscow-backed separatists. A separatist official said others were hospitalized.
It was not clear how many fighters were left in the maze of tunnels and bunkers at the plant. Russia in recent weeks had estimated that it had been battling some 2,000 troops at the steelworks.
The International Committee of the Red Cross said that it has registered hundreds of POWs from the plant under an agreement between Russia and Ukraine. It did not say whether it had visited the prisoners.
While Ukraine said it hopes to get the soldiers back in a prisoner swap, Russian authorities have threatened to investigate some for war crimes and put them on trial, branding them ``Nazis'' and criminals.
The defense of the steel mill has been led by Ukraine's Azov Regiment, whose far-right origins have been seized on by the Kremlin as part of its effort to cast its invasion as a war against Nazi influence in Ukraine.
Those threats and accusations have raised fears of Russian reprisals against the captured fighters.
Amnesty International had pushed for the Red Cross to be given access to the troops, citing lawless executions allegedly carried out by Russian forces in Ukraine and saying the Azovstal defenders ``must not meet the same fate.''
The emptying of the plant would allow Russia to claim complete control of Mariupol, a long-sought victory but one that holds largely symbolic importance at this point since the city is already effectively under Moscow's control and military analysts say most of the Russian forces that were tied down by the drawn-out fighting have already left.
Still, it would be a clear win in a war that has seen Moscow suffer a series of setbacks in the face of unexpectedly stiff Ukrainian resistance. Kyiv's troops, bolstered by Western weapons, thwarted Russia's initial goal of storming the capital and have tied down Moscow's forces in the Donbas, the eastern industrial region that President Vladimir Putin now has his sights on capturing.
The surprising success of Ukraine's troops in the face of a larger and better armed force has buoyed Kyiv's confidence, and a senior official reflected that Thursday.
Mykhailo Podolyak, an adviser to Ukrainian President Volodymyr Zelenskyy who was involved in several rounds of talks with Russia, said in a tweet addressed to Moscow: ``Do not offer us a cease-fire _ this is impossible without total Russian troops withdrawal.''
``Until Russia is ready to fully liberate occupied territories, our negotiating team is weapons, sanctions and money,'' he wrote.
But Russia signaled its intent to exert its influence over areas its forces have seized during Russia's invasion. Russian Deputy Prime Minister Marat Khusnullin visited the Kherson and Zaporizhzhia regions this week, which have been under control of Russian forces since shortly after the invasion began in February. He was quoted by Russian news agencies as saying they would be part of ``our Russian family.''
Also, Volodymyr Saldo, the Kremlin-appointed head of the Kherson region, appeared in a video on Telegram telling regional officials that Kherson ``is controlled by the armed forces of the Russian Federation, but in the future it will become a subject of the Russian Federation.''
Sweden and Finland, fearing that Putin's ambitions extend beyond Ukraine, applied this week to join NATO and gain its protection against Russia, though the process has been thrown into jeopardy by NATO member Turkey.
Turkey has accused the two Nordic countries of harboring or otherwise supporting Kurdish militants and others it considers a threat to its security. Each of NATO's 30 countries has an effective veto over new members.
``We have told our relevant friends we would say `no' to Finland and Sweden's entry into NATO, and we will continue on our path like this,'' President Recep Tayyip Erdogan said in a video released Thursday.
On the battlefield, Ukraine's military said Russian forces pressed their offensive in various sections of the front in the Donbas but were being repelled. The governor of the Luhansk region said Russian shelling killed four civilians, while separatist authorities in Donetsk said Ukrainian shelling killed two.
On the Russian side of the border, the governor of Kursk province said a truck driver was killed by shelling from Ukraine.
In the war crimes trial in Kyiv, Sgt. Vadim Shishimarin, a 21-year-old member of a Russian tank unit, told the court that he shot Oleksandr Shelipov, a 62-year-old Ukrainian civilian, in the head on an officer's orders.
Shishimarin said he disobeyed a first order but felt he had no choice but to follow the order when it was repeated by another officer. He said he was told the man could pinpoint their location to Ukrainian forces.
A prosecutor has disputed that Shishimarin was acting under orders, saying the direction didn't come from a direct commander.
Shishimarin apologized to the victim's widow, Kateryna Shelipova, who described seeing her husband being shot just outside their home in the early days of Russia's invasion.
She told the court that she believed Shishimarin deserves a life sentence, the maximum possible, but that she wouldn't mind if he were exchanged as part of a possible swap for the defenders of the Azovstal plant.