The Russian forces have been fighting Ukrainian forces as well as an international legion.

Tens of foreign mercenaries have been killed in Ukraine over the past 10 days, according to Russian Defense Minister, Sergey Shoigu.

Shoigu spoke at a ministry meeting, saying that as a "result of the successful offensive" by both the Russian and Donbass republics' forces, “the number of foreign mercenaries and employees of private military companies operating in the country has decreased.”

“Over the past 10 days, 170 foreign mercenaries have been killed, 99 have refused to participate in combat and left the territory of Ukraine,” he said.

On Tuesday, Damien Magrou, a spokesperson for the International Legion of Territorial Defense of Ukraine, confirmed that a French fighter that goes by the name Adrien D was killed in Kharkov. The legion is a foreign military unit created at the start of the war at the request of Ukrainian President Volodymyr Zelensky.

The fighter died of injuries on June 25 after spending some time in a coma at a hospital, and he was one of the first foreign fighters to join the Ukrainian ranks - and, the second French national to die.

On June 1, Wilfried Bleriot, his colleague, was also killed in the same region.

According to RTL, there are reports that around 50 French nationals fighting for Ukraine, and Magrou revealed that foreigners from 55 countries serve in the region, with most coming from Poland, the US, UK, and Canada.

Magrou added that the foreigners “are servicemen in the Ukrainian Armed Forces,” and that they should be considered prisoners of war protected by the Geneva Conventions.

“We hereby call on Russian authorities and Russian proxies to respect international humanitarian law and refrain from politically motivated criminal proceedings against lawful members of the Ukrainian Armed Forces," Magrou said in a statement.

In response, Kremlin Spokesperson Dmitry Peskov said, "They are not (in the) Ukrainian army, so they are not subject to the Geneva Conventions."

"They're soldiers of fortune and they were involved in illegal activities on the territory of Ukraine. They were involved in firing and shelling our military personnel. They were endangering their lives," Peskov said.

"They should be held responsible for those crimes that they have committed," he added. "Those crimes have to be investigated."

Russian Military Spokesperon Major General Igor Konashenkov last month said that hundreds of foreign mercenaries in Ukraine have been killed by Russian long-range precision weapons “shortly after their arrival at the places where they were undergoing additional training and where the tactical units were coordinated.” However, most of them, according to the Spokesperson, were killed “due to a low level of training and a lack of real combat experience.”

Russian Defense Ministry data revealed that 6,956 foreign citizens from 64 countries arrived in Ukraine to fight alongside Ukrainian troops between February 24 and June 17. Around 1,956 of those have been killed, while 1,779 have left the country, the Ministry said.

Two new British mercenaries charged in DPR

Dylan Healy, 22, and Andrew Hill, 35, both UK nationals, were captured by DPR forces during fighting in April.

British broadcaster Sky News described Hill as a "military volunteer". Hill was charged on Tuesday by DPR forces alongside Healy for acting as mercenaries for Ukraine's armed forces.

Russia's TASS news agency reported that both men have refused to cooperate and are currently imprisoned in the DPR.

"Criminal cases have been initiated and charges were presented for (mercenarism) against British citizens Dylan Healy and Andrew Hill, currently in detention in DPR. Investigation operations are under way as the investigators look for evidence of the crimes, committed by the British, because they do not want to testify and refuse to cooperate on their criminal cases," a DPR source informed TASS.

Britain's Foreign Office released a statement on Saturday condemning "the exploitation of prisoners of war and civilians for political purposes."

"We are in constant contact with the government of Ukraine on their cases and are fully supportive of Ukraine in its efforts to get them released," the statement added.