Foreign Secretary Liz Truss will hold talks her Ukrainian counterpart today after two Brits fighting in Mariupol were sentenced to death by pro-Russian officials in a “disgusting Soviet-era show trial”.
The Cabinet minister will speak to Ukraine ’s Foreign Minister Dmytro Kuleba by phone after she condemned the “sham” judgement against Aiden Aslin and Shaun Pinner.
It is understood the meeting has been in the diary for a few days but the case will be raised.
But the Foreign Secretary has resisted holding direct talks with Russia - as demanded by one of the two men's local MP Robert Jenrick, who wants her to summon the Russian Ambassador.
UK officials claim it would give credibility to Russia’s "sham" claims that the men are mercenaries.
Aiden Aslin, 28, and Shaun Pinner, 48, were convicted of taking action towards violent seizure of power at a court in the self-proclaimed Donetsk People's Republic.
A third man, Moroccan national Saaudun Brahim, was convicted alongside Mr Aslin and Mr Pinner.
The UK maintains that as members of the Ukrainian army the men are prisoners of war and therefore should be protected by international law.
Britain believes the men are being exploited for Russia’s political ends and it could end in a prisoner swap between Russia and Ukraine.
Robert Jenrick, Tory MP for one of the two men, told the Mirror: "If it is resolved it's going to be via a prisoner exchange. Both sides have at least a couple of thousands of the other side's personnel."
He added: “This disgusting Soviet-era show trial is the latest reminder of the depravity of Putin’s regime.”
Ms Truss said yesterday: “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.”
A Foreign Office Spokesperson said: “We are working with the government of Ukraine on the detention of British Nationals.
“We condemn the exploitation of Prisoners of War for political purposes. They are entitled to combatant immunity and should not be prosecuted for participation in hostilities.”
Mr Aslin, originally from Newark-on-Trent in Nottinghamshire, and Mr Pinner were both members of regular Ukrainian military units fighting in Mariupol, the southern port city which was the scene of some of the heaviest fighting since Vladimir Putin's invasion of Ukraine.
Mr Aslin is thought to have a Ukrainian partner and other members of his family are still in Newark where they are prominent members of the local community.
Mr Jenrick, who represents the Newark constituency, called for the Russian ambassador to the UK to be summoned to the Foreign Office.
He said it "has been a fraudulent show trial, we shouldn’t give it any credibility whatsoever", adding: “They’re not mercenaries, they are British citizens who chose to join the Ukrainian army for personal reasons before Putin’s invasion of Ukraine.”
It comes after a friend of Mr Aslin said the death sentences will "invigorate" those still resisting Russia's advances.
Brennan Phillips, an American former soldier who met Mr Aslin in Syria and worked alongside him in Ukraine, said the judgement is a "provocation".
Speaking to BBC Newsnight, Mr Phillips said: "I think it will invigorate people more than anything.
"Whatever effect they thought they would have in this provocation, I don't think that and I don't think it's going to be well-received. And they did this as a provocation."
Tory MP Bob Seely, who sits on the foreign affairs select committee, accused Russia of breaking international law.
"I very much hope they are not killed quickly - they may be killed quickly as shock value," the Isle of Wight MP told the BBC.
"But if, as everyone expects, they are not then they will be held as a diplomatic tool and I think the bigger picture here - what is happening - is that the Russians are going to become increasingly aggressive as part of the indirect conflict against the Baltic republics, against the Poles, against the UK and others who are close to the Ukrainian government and are supporting the Ukrainians in the conflict."
A No 10 spokesman said: "We are obviously deeply concerned by this. We have said continually that prisoners of war shouldn't be exploited for political purposes.
"Under the Geneva Convention, prisoners of war are entitled to combatant immunity and they should not be prosecuted for participation in hostilities.
"So we will continue to work with the Ukrainian authorities to try to secure the release of any British nationals who were serving in the Ukrainian armed forces and who are being held as prisoners of war."
