Wagner chief Yevgeny Prigozhin said Sunday he won't sign any contracts with the Russian Ministry of Defense, after the ministry announced Saturday that "volunteer units" and private military groups like Wagner will be required to sign a contract with the ministry by July 1, "in order to increase the efficiency of their use."

"The orders and decrees issued by (Defense Minister Sergei) Shoigu apply to employees of the Ministry of Defense and military personnel. PMC 'Wagner' will not sign any contracts with Shoigu,” Prigozhin said in a Telegram post.

However, Wagner would "absolutely" pursue "the interests of the Russian Federation and the Supreme Commander-in-Chief,” Prigozhin said.

The Russian Defense Ministry said in a statement Saturday, quoting a decree signed by Shoigu, that such contracts would "give the voluntary formations the necessary legal status," and create "unified approaches" to their work and "the fulfillment of their tasks."

Some key context: Prigozhin has frequently criticized Russia’s traditional military hierarchy as he sought to win a power struggle against military commanders to lead the ground effort in eastern Ukraine for Russian President Vladmir Putin — with whom he remains closely allied.

Earlier this month he blamed Russian defense chiefs for “tens of thousands” of Wagner casualties because they didn’t have enough ammunition.

Prigozhin is often known to speak sarcastically, and at times has reversed on comments he has made in strongly worded public remarks.