KYIV, Ukraine (AFP)— Russia said Tuesday that 265 Ukrainian soldiers had surrendered after staging a last stand at the besieged Azovstal steelworks in Mariupol, prompting Kyiv to call for a prisoner exchange.

Moscow claimed control of the strategic port city last month after a weeks-long siege, but hundreds of Ukrainian soldiers remained holed up in tunnels beneath the huge Azovstal industrial zone.

“Over the past 24 hours, 265 militants laid down their arms and surrendered, including 51 heavily wounded,” the Russian defence ministry said.

Publishing images showing wounded soldiers being carried on stretchers, it said the injured were taken to a hospital in the eastern Donetsk region controlled by pro-Kremlin rebels.

Elsewhere, lawmakers in Finland — which shares a 1,300-kilometre (800-mile) border with Russia — voted overwhelmingly in favour of joining the NATO military alliance.

The vote paves the way for a joint application with Sweden to be submitted on Wednesday, amid fears they could be Russia’s next targets.

Meanwhile, Kyiv said negotiations with Russia on ending the near three-month war, which has killed thousands and sent millions fleeing, were “on hold”, blaming Moscow for failing to compromise.

Ukraine’s defence ministry confirmed the soldiers had left Azovstal, expressing hope for an “exchange procedure… to repatriate these Ukrainian heroes as quickly as possible”.

For those remaining in the warren of tunnels underneath the steelworks, it said it was doing “everything necessary for their rescue” — although a military intervention was not possible.

In Moscow, Kremlin spokesman Dmitry Peskov did not answer questions about whether the Azovstal soldiers would be treated as war criminals or prisoners of war.

President Vladimir Putin “guaranteed that they would be treated according to the relevant international laws,” he said.

Ukraine has accused Moscow of war crimes during the conflict, notably in the town of Bucha near Kyiv, where AFP reporters saw at least 20 bodies lying in the streets after Russian forces withdrew in late March.

The International Criminal Court said Tuesday it was deploying its largest-ever field team to Ukraine, comprising 42 investigators, forensic experts and support staff.