Fierce fighting continues between Russian and Ukrainian forces for control of Ukraine's eastern stronghold of Bakhmut in the Donetsk region. Russian forces are believed to have seized the eastern side of the city.

A Ukrainian army commander said on social media on Monday that the situation around Bakhmut remains difficult.

He said Russian Wagner Group mercenaries are attacking from several directions trying to break through the defenses of his troops and advance to the central districts of the city.

But he added all enemy attempts to capture the city are being repelled by artillery, tanks and other firepower.

Wagner's head, Yevgeny Prigozhin, said in an audio recording posted to social media on Sunday that the situation in Bakhmut is very tough. He said, "The closer we are to the center of the city, the harder the fighting."

A US think tank, the Institute for the Study of War, said on Sunday that the conflict between Russia's defense ministry and Wagner Group financier Prigozhin "likely reached its climax" against the backdrop of the Battle of Bakhmut.

It said Russian President Vladimir Putin had ultimately allowed the defense ministry to retake control of the Bakhmut operation from Prigozhin in January as Wagner forces failed to deliver the promised victory over the city by the end of 2022.

The institute said Putin and the defense ministry may use Prigozhin as a scapegoat for the costly drive on Bakhmut once the offensive ends.

The British defense ministry said in its intelligence update on Monday that about half of the prisoners Wagner has already deployed in Ukraine have likely become casualties.

The ministry said that in recent weeks, Prigozhin has likely lost access to Russian prisoners to fill his ranks due to his ongoing disputes with Russia's defense ministry.

It added his efforts to hire free Russian citizens are unlikely to make up for the loss of the convict recruit pipeline.