However, Denis Pushilin, the head of the DPR, which is unrecognized internationally, played down this prospect in comments reported by Russian media last week.
“First of all, I must be guided by the court decision that has been made,” he said.
“By the nature of those articles, those offenses that they committed, I see no grounds or prerequisites for me to pardon them.
“They came to Ukraine to kill civilians for money. That’s why I don’t see any conditions for any mitigation or modification of the award.”
He added the court had “issued a perfectly fair punishment” to the three fighters.
The Britons were legal combatants serving with Ukraine’s armed forces and fully entitled to protection for prisoners of war under the Geneva convention, British ministers have previously insisted.
Liz Truss, the foreign secretary, said she had discussed the case with her Ukrainian counterpart, Dmytro Kulebo, earlier this month.
Mr Aslin, 28, is a former care worker from Newark and Mr Pinner, 48, is a former British soldier with the Royal Anglian Regiment. They had both moved to Ukraine in 2018 and signed military contracts with the Ukrainian army.
The family of Brahim Saadoune said that he had signed up as a contract soldier in the Ukrainian army in 2021.