Two Britons captured by Russian forces appeared in a rebel court after having been accused of being mercenaries for the Ukrainian army.
Aiden Aslin, 28, and Shaun Pinner, 48, are being held in a court in the so-called Donetsk People’s Republic.
If the men are convicted of the charges, which include trying to “seize power”, it is feared the court, which is not internationally recognised, could pass the death penalty.
They were both members of regular Ukrainian military units in Mariupol and are also accused of violent seizure of power and undergoing training to carry out terrorist activities.
The affiliation of a third British man, Andrew Hill, who was captured in the Mykolaiv area, is unclear.
Footage of three men, reported to be Mr Aslin, Mr Pinner and Saaudun Brahim, a Moroccan national, in what appears to be a court dock emerged on Tuesday.
They spoke only to confirm they were aware of the charges they face and say they consented to their case proceeding without witness evidence, according to the BBC.
Separatist president Denis Pushilin on Monday claimed “the crimes they committed were monstrous”, according to separatist news agency DAN.
Tory former minister Robert Jenrick said Mr Aslin has been victim to a “completely outrageous breach of international law”.
He told BBC Radio 4’s World at One programme: “This is a British citizen, but who also holds Ukrainian nationality, is married to a Ukrainian, joined the Ukrainian armed forces in the normal way prior to [Vladimir] Putin’s illegal invasion, and has been serving in the armed forces.
“He was taken prisoner by Russian forces and in accordance with international law and the Geneva Convention, he should be being held appropriately and returned to Ukraine at the earliest possible opportunity, possibly through a prisoner exchange.
“Instead of that Putin’s regime have chosen to put him and another British national, Shaun Pinner, on trial on trumped-up charges, no evidence whatsoever.”
Mr Aslin‘s family said in the statement on Tuesday: “We, the family of Aiden Aslin, wish to ask for privacy at this time from the media.
“We are currently working with the Ukrainian government and the Foreign Office to try and bring Aiden home.”
Justice secretary Dominic Raab has said the UK Foreign Office will “make all the representations” on Mr Aslin‘s behalf.
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