Ukraine celebrates release of over 200 captives in surprise swap with Russia

Ukraine has celebrated the release of more than 200 of its citizens from Russian captivity, including the fighters who led the defence of the Azovstal steelworks in Mariupol.

It was the biggest prisoner swap since the start of Russia’s invasion in February, and came as a surprise during a week in which the Kremlin raised the stakes again in Ukraine, promising to hold sham “referendums” to annex Ukrainian territory and threatening nuclear strikes if thwarted.

“We have freed 215 of our people from captivity, of whom 124 are officers. Of those we have freed, 108 are Azov fighters,” said Andriy Yermak, chief of staff to the Ukrainian president, Volodymyr Zelenskiy.

Others released by Russia included Ukrainian border guards and police officers, said Zelenskiy. Moscow also released 10 foreigners, including five Britons and two Americans.

In return, Ukraine released 55 captured Russian soldiers, as well as the former Ukrainian MP Viktor Medvedchuk, an ally of Vladimir Putin accused by Ukraine of high treason.

The swap came after mediation by Turkey, with negotiations carried out in strict secrecy.

“We knew that negotiations were ongoing, but we didn’t know the details. Of course it was a surprise that the commanders were freed,” said Tetiana Kharko, the sister of Serhii Volynskyi, a Ukrainian marine commander who took part in the defence of Azovstal, the last holdout of Ukrainian forces in the southern city of Mariupol that Russia took control of after reducing much of it to rubble.

The Azovstal defenders surrendered in May after a long siege. They had refused to give up for weeks despite running out of ammunition and with many wounded in the underground tunnels of the vast Azovstal plant. Since then they have been held in Russian captivity.

Kharko said she had been able to speak to her brother for a few minutes after he arrived in Turkey following his release. “I felt euphoric to hear his voice. I just said his name over and over again,” she said, adding that the call was brief and they had not discussed the conditions of his detention in Russia.

Volynskyi is one of five commanders to be released who will have to stay in Turkey. Zelenskiy said the five would stay there “in total security and in comfortable conditions” until the end of the war.

Many of the Azovstal defenders were from the Azov regiment, first formed as a volunteer battalion in 2014, when many of its members had far-right leanings.

Related: Who is Viktor Medvedchuk and why does his arrest matter to the Kremlin?

Russia has previously described the Azov regiment fighters as “neo-Nazis” and made frequent public statements about wanting to hold a “Nuremberg 2.0” show trial, to justify its false claims that its war in Ukraine is about the “denazification” of the country. Russia’s embassy in Britain tweeted in July that the fighters should be hanged. “They deserve a humiliating death,” it said.

Russia also released 10 foreigners, including two Britons who had been sentenced to death by a court in the self-proclaimed republic of Donetsk, in a part of the deal that was brokered separately by Saudi Arabia’s crown prince, Mohammed bin Salman.

Russian propagandists scrambled on Thursday to explain why the exchange appeared lopsided, while there was anger among some military bloggers that so much attention had been paid to Medvedchuk, released by Ukraine as part of the deal.

Chechnya’s leader, Ramzan Kadyrov, criticised Russia’s leadership in unusually harsh terms on Thursday, saying “terrorist criminals should not be swapped for soldiers”. He also said the swap would mean that Chechen troops fighting as part of Russian forces in Ukraine would “draw their own conclusions and not take fascists prisoner”.

Medvedchuk is a Ukrainian citizen who ran a pro-Russia political party before the outbreak of the war and was known as Putin’s closest ally in Ukraine. The Russian president is godfather to his daughter.

Medvedchuk was arrested in April after escaping house arrest on treason charges days after Russia launched its invasion. Zelenskiy called on Russia at the time to exchange him for Ukrainian prisoners of war, but the Kremlin rejected the offer.

In a statement about the swap, Zelenskiy said Ukraine had got a good deal.

“I am not sad about swapping Medvedchuk for real warriors. He has gone through all investigative procedures according to the law and Ukraine has got everything from him it needs to determine the truth,” he said.

Related: ‘I will cross the border tonight’: Russians flee after news of draft

Away from the prisoner swap, fighting continued on the ground on Thursday. Russian missile strikes hit the centre of the city of Zaporizhzhia, killing one and wounding five, Ukrainian officials said. In Donetsk, Russian proxy authorities claimed that Ukrainian shelling had killed six people.

In a televised announcement on Wednesday morning, Putin said he was mobilising part of Russia’s reserves, and also said Russian occupation authorities would go ahead with so-called “referendums” in four Ukrainian regions, even though the Russian army does not control all the territory to which it is laying claim.

The sham votes have been widely condemned internationally, but look set to provide a pretext for Russia to declare it is annexing the territory.

Putin said on Wednesday that Russia would be prepared to use nuclear weapons to protect itself. On Thursday, the former president Dmitry Medvedev, who is now the deputy chair of Russia’s security council, said nuclear weapons could be used to defend the new territories that Russia planned to claim.

“Any Russian weapons, including strategic nuclear weapons and weapons based on new principles, could be used for such protection,” he said.

Ukrainian officials have called for a tough response from western leaders to the Russian threats.