The British foreign secretary, Liz Truss, will raise the case of two Britons sentenced to death for fighting Russian forces when she speaks with her Ukrainian counterpart.
Aiden Aslin, 28, and Shaun Pinner, 48, have been convicted of taking action towards violent seizure of power at a court in the self-proclaimed republic in Donetsk.
Truss has called it a “sham judgment” and said it had “absolutely no legitimacy”.
She will speak about the matter during a phone call with Dmytro Kuleba later on Friday, the BBC said, while No 10 has said the men are entitled to combatant immunity as prisoners of war.
Truss said: “I utterly condemn the sentencing of Aiden Aslin and Shaun Pinner held by Russian proxies in eastern Ukraine. They are prisoners of war. This is a sham judgment with absolutely no legitimacy. My thoughts are with the families. We continue to do everything we can to support them.”
An adviser to the Ukrainian interior minister said on Friday that Russia had the men sentenced to death in order to gain leverage in their negotiations with Ukraine and its western allies.
“The trial of the foreigners raises the stakes in the Russian Federation’s negotiation process. They are using them as hostages to put pressure on the world over the negotiation process,” said Vadym Denysenko in televised remarks.
He said Ukraine would coordinate its position on the sentences with Britain, the US and the EU. Ukraine has already sentenced several Russian soldiers to long prison terms for war crimes and Russia may seek to trade the prisoners to get them back.
For now, Russia has claimed it has no influence on the proceedings, which took place in a Russian-occupied territory in east Ukraine.
“I’d rather not hinder the operation of the judiciary and law enforcement authorities of the Donetsk People’s Republic,” said the Russian foreign minister, Sergei Lavrov, referring to the proxy government.
The MPs who represent the two men as constituents, Robert Jenrick, the MP for Newark, and Richard Fuller, the MP for North East Bedfordshire, have called for Russian officials to be summoned to answer for their proxies’ actions in the Ukrainian region.
Speaking on BBC Radio 4’s Today programme, Jenrick said: “I’ve urged the foreign secretary to raise this immediately at the highest levels with the Russian government. The UK needs to be clear you can’t treat British nationals in this way. This really is the most egregious breach of international law.”
He added: “Aiden and Shaun are not mercenaries, they are combatants, who are prisoners of war now and should be treated in accordance with the Geneva conventions and the Geneva convention is being breached in the most egregious manner by Russia in holding this kangaroo court and now this sentence to death.”
Jenrick said the men were being “hooked out and used in a Soviet-era show trial as a way of taking hostages or taking revenge against the UK”.
He said a prisoner exchange could be a solution but that required Russia to “play ball, take this issue seriously and start living up to their international obligations”.
Fuller said the men needed access to healthcare and legal advice. He said it was “fair” to argue they had exposed themselves to risk, but added: “What’s at the centre of this is the recognition by the Russian authorities and their proxies in this region that Shaun and Aiden were members of the Ukrainian military they are prisoners of war, and that the Geneva convention applies. There appears to be no recognition of that.”
On Friday morning, the school standards minister, Robin Walker, said the government would use all diplomatic channels to raise the case.
He told Sky News: “We utterly condemn the approach that’s been taken here and we will use every method at our disposal to take this issue up.”
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A third man, the Moroccan national Saaudun Brahim, was convicted alongside Aslin and Pinner. The men were accused of being mercenaries after fighting with Ukrainian troops.
The Russian news agency Interfax claimed the men would be able to appeal against their convictions.
Aslin, originally from Newark-on-Trent in Nottinghamshire, and Pinner were members of regular Ukrainian military units fighting in Mariupol, the southern port city that was the scene of some of the heaviest fighting since Vladimir Putin’s invasion of Ukraine.
