Wagner boss Yevgeny Prigozhin on Thursday said an ammunition shipment is on its way to his fighters in Ukraine after he accused Russia’s defense establishment earlier this week of creating “major problems” with supplies for the mercenary group.

In a message and voice note published on his Telegram channel Thursday, Progozhin said the shipment began at 6 a.m. local time.

"Most likely, the train has started moving…we are told that the main papers have already been signed,” the message read. “I would like to thank all who helped us accomplish this. You saved hundreds, maybe thousands of lives of men who are defending their homeland.”

Public spat: On Tuesday, Prigozhin accused the Russian Defense Ministry's leadership of "treason" for failing to get ammunition to Wagner fighters and "not helping with air transport."

CNN has not been able to independently verify Prigozhin's claims about ammunition shortages. The Wagner chief, who has no official position, has repeatedly blamed the Russian Ministry of Defense for battlefield losses in Ukraine.

The US government estimates the Wagner group has suffered more than 30,000 causalities, including roughly 9,000 dead in the battle for the city of Bakhmut. About half of those 9,000 have been killed since mid-December, US National Security Council spokesperson John Kirby said last week. And about 90% of those killed in December were recruited from Russian prisons, he said.