- Russian and Wagner troops opened fire on each other in Luhansk over an argument, Ukraine says.
- The soldiers and mercenaries had been blaming each other for their mistakes in the war, per Ukraine.
- Russia has yet to confirm the report, which Insider could not independently verify.
Ukraine said on Sunday that a group of Russian troops and Wagner mercenaries opened fire on each other over a dispute about their wartime mistakes.
Soldiers from both forces were killed in the shootout in Luhansk, an eastern Ukrainian region occupied by Russia and Kremlin-backed rebels, the General Staff of the Armed Forces of Ukraine wrote in its daily briefing on Sunday.
The Wagner Group is not officially part of the Russian army, but has been enlisted by the Kremlin to fight alongside Moscow's troops in Ukraine.
Both sides clashed as they blamed each other for defeats in Ukraine, the update claimed.
"They shift the responsibility for their own tactical miscalculations and losses suffered onto each other," the briefing said. "As a result, a fight between Russian Armed Forces and PMC Wagner mercenaries broke out in the settlement of Stanytsia Luhanska recently."
Russia has not confirmed Ukraine's Sunday report. Insider could not independently verify Ukraine's claim about the shootout.
The report also comes as Wagner's relationship with the Kremlin appears to be deteriorating while the mercenary group takes heavy losses.
Yevgeny Prigozhin, the mercenary group's founder who's thought to be a close ally of Russian President Vladimir Putin, in March complained that Russia's top military brass was ignoring his requests for more ammunition.
"To get me to stop asking for ammunition, all the hotlines to office, to departments, etc., have been cut off from me," Prigozhin said.
But Wagner has still been working closely with Russia's regular forces, with its ground forces deployed in tandem with Russian air support and artillery, Michael Kofman, director of the Russia Studies Program at the Center for Naval Analyses think tank, told Insider's Michael Peck.
It's thus unclear whether the alleged firefight represents wider conflict or discipline issues among Russian forces on the frontline. Wagner has been deploying poorly trained Russian convicts in Ukraine, almost 30,000 of whom have died, per US officials.
However, multiple reports have documented Russian troops being plagued by friendly fire in Ukraine, though the Kremlin rarely acknowledges any of these incidents.
Russia's combat formations and systems also made it difficult for its forces to identify friend from foe in the early months of the war, the Royal United Services Institute, a UK think tank, found in November.
But accounts of Russian friendly fire continued to emerge later in the war, including instances that appeared intentional.
British intelligence reported in November that Russia was deploying "blocking units" behind its soldiers to prevent them from retreating.
"These units threaten to shoot their own retreating soldiers in order to compel offensives and have been used in previous conflicts by Russian forces," the UK Ministry of Defense said.
And in December, Ukrainian intelligence said it intercepted a call from a Russian soldier to his mother, in which he said his comrades were taking more losses "from their own side" than from Ukrainian fire.
In a rare admission on Friday, Russia's defense ministry said one of its Su-34 jets accidentally bombed the Russian city of Belgorod. Local authorities said the blast injured two women and damaged four apartments.
Russia's Defense Ministry did not immediately respond to Insider's requests for comment.