The Kremlin says the United Kingdom should address the leaders of separatist-controlled parts of Ukraine’s Donetsk region and not Moscow over two Britons sentenced to death last week for fighting alongside Ukrainian forces against Russian troops in eastern Ukraine.

Kremlin spokesman Dmitry Peskov told reporters in Moscow on Tuesday that British authorities had not turned to Moscow regarding the fate of Aiden Aslin and Shaun Pinner who, along with Moroccan national Saaudun Brahim, were sentenced to death on June 9 for “mercenary activities” by what separatists called the Supreme Court of the Donetsk People’s Republic.

“They should address the authorities of the country that pronounced the sentences, and that is not the Russian Federation,” Peskov said.

Britain, the United Nations, Ukraine, and Germany have condemned the death sentences.

Aslin’s family said he and Pinner were living in Ukraine when the war broke out in February and “as members of Ukrainian armed forces, should be treated with respect just like any other prisoners of war.”

The father of Saaudun Brahim said on June 13 that his son is also a Ukrainian citizen and should be treated accordingly.

Britain has condemned the sentencing of its citizens as an “egregious breach” of the Geneva Convention, under which prisoners of war are entitled to combatant immunity and should not be prosecuted for participating in hostilities.

British Foreign Secretary Liz Truss said on June 14 that she would do whatever was necessary to secure the release of the two.

“I have assured the families that I will do what is most effective to secure their release and I am not going to go into our strategy live on air…The best route is through the Ukrainians,” she told BBC Radio.

Ukrainian Deputy Prime Minister Iryna Vereshchuk said on June 11 that she believed the separatist authorities would ultimately act rationally, “for they are well aware of the irreparable implications for them and for the Russians if they take any wrong steps against these three of our soldiers.”

Among U.N. member states, only Russia recognizes the entire Ukrainian province of Donetsk as the Donetsk People’s Republic. The territory is internationally recognized as part of Ukraine.