The death sentences come as Moscow concentrates its firepower on the strategic industrial hub of Severodonetsk, where Ukrainian President Volodymyr Zelensky said forces are “holding on” amid fierce fighting that he earlier said could determine the fate of the entire Donbas area.
Separatist authorities in the Donetsk region of the Donbas ordered the death penalty for Aiden Aslin, Shaun Pinner and Saadun Brahim after they were accused of acting as mercenaries for Kyiv, Russian media reported.
Britain said it was “deeply concerned” by the sentences.
“Under the Geneva Convention, prisoners of war are entitled to combatant immunity,” said a spokesman for Prime Minister Boris Johnson.
Britons Aslin and Pinner surrendered in April in Mariupol, the southern port city that was captured by Russian troops after a weeks-long siege. They later appeared on Russian TV calling on Johnson to negotiate their release.
Brahim surrendered in March in the eastern town of Volnovakha.
During a trial that lasted three days, the men pleaded guilty to committing “actions aimed at seizing power and overthrowing the constitutional order of the Donetsk People’s Republic”, Russian news agency Interfax said.
A lawyer representing one of them told the TASS news agency that they would appeal.
Western countries have provided weapons and aid for Ukraine since the Feb 24 invasion, while a number of people from abroad have come to fight against Russian forces.
The fiercest fighting is now focused on Severodonetsk in the Lugansk region, where Ukrainian officials say their outgunned forces are still holding out amid street battles, despite the city being mostly under Russian control.
The regional governor of Lugansk - also part of the Donbas - said Western artillery would quickly help secure a Ukrainian victory for the bombarded city.
“As soon as we have long-range artillery to be able to conduct duels with Russian artillery, our special forces can clean up the city in two to three days,” governor Sergiy Gaiday said.
In his evening address to the Ukrainian people yesterday, Zelensky said Severodonetsk and other Donbas cities “are holding on”.
Kyiv’s forces were also “gradually moving forward in the Kharkiv region” in the northeast, he added.
Up to 100 Ukrainian soldiers were being killed every day in frontline fighting and as many as 500 wounded, Defence Minister Oleksiy Reznikov said.
After being repelled from Kyiv weeks into their invasion, Russian President Vladimir Putin’s troops have refocused their offensive on the Donbas.
Pro-Russian separatists have held part of that region since 2014.
Moscow, which has repeatedly warned the West against getting involved in the conflict, said it had targeted a Ukrainian training centre for “foreign mercenaries” in the Zhytomyr region, west of Kyiv.
The Ukrainian presidency said four people were killed in a Russian air strike on Toshkivka, a village around 25 kilometres south of Severodonetsk.
Four more people were killed in fighting in Donetsk and shelling took the lives of two in Kharkiv city, it said. Another person was killed in the Mykolayiv region in the south.
In Kyiv, Ukraine’s Interior Minister Denys Monastyrsky said the capital was in no immediate danger, but troops were keeping up a line of defence around the city all the same.
Putin, meanwhile, compared his actions to Peter the Great’s conquest of the Baltic coast during his 18th century war against Sweden.
“By fighting Sweden he was grabbing something... He was taking it back,” he told young entrepreneurs in Moscow.
“It is our responsibility also to take back and strengthen,” Putin said, in an apparent reference to Russia’s invasion of Ukraine.
‘Every day something burns’
Zelensky yesterday called for Russia to be expelled from the UN’s Food and Agriculture Organization (FAO), blaming Moscow for “causing hunger” and spurring the global grain crisis by invading his country.
Ukraine’s Black Sea ports usually export millions of tonnes of grain each year but have been blocked since the invasion, while western sanctions on Russia have prevented Moscow selling much of its grain abroad, sending food prices soaring.
The FAO warned that poor countries will suffer the most from the crisis as they were “paying more but receiving less food”.
Africa has been hard hit by the shortage, and the African Union (AU) yesterday urged Kyiv to demine waters around Ukraine-controlled Odessa port to ease exports, warning of “serious famine” and destabilisation on the continent.
Moscow has also called for Ukraine to demine to allow out blocked grain, but Kyiv has refused for fear of a Russian attack.