Ukrainian forces are advancing in East Ukraine and have vowed to take advantage of an unfolding “civil war” in Russia, as Vladimir Putin faces an armed insurrection by the country’s most powerful mercenary group. In a direct threat to Putin’s authority, Yevgeny Prigozhin, the leader of Wagner, accused Moscow’s military of bombing his men and seized control of a key Russian city on Saturday morning. The outspoken leader of the world’s most infamous private army promised to march on the capital to get his revenge. In an unprecedented speech, Mr Putin called the act “treason” and said those who “took the part of blackmail and terrorist method will suffer inevitable punishment”. Ukrainian President Zelensky broke his silence to say it was another example of “Russia’s full-scale weakness”. Watching eagerly from across the frontlines, Ukrainian commanders, defence ministry officials and soldiers, told The Independent the country was “maximising” the extraordinary implosion of military leadership in Russia to push forward with their much-anticipated counter-offensive. Soldiers on the ground, speaking on the condition of anonymity, said overnight they had already advanced on the battle-ravaged Bakhmut in the eastern region of Donbas. Wagner forces have largely spearheaded Russia’s advance on the city which has been locked in a bloody stalemate that it earned the moniker of “meat grinder”. “Without a doubt, we will take advantage of this, as you will see in the near future,” Serhiy Cherevaty, spokesperson for the Ukrainian Armed Forces in the east, told The Independent, adding that Ukraine had long waited for Russia’s “irregular”’ reliance on mercenaries to backfire. “We predicted this would happen sooner or later and would lead to a larger escalation,” he continued. “Prigozhin is a media mogul, he has a powerful troll factory, a network of telegram channels, and has bought military journalists. All this is seen by [Russia’s] military personnel, and it demoralises them. “We will definitely take advantage of the enemy's confusion.” Yuriy Sak, a top advisor to Ukraine's defence minister, told The Independent that the Ukrainian leadership was closely watching a “real military coup”. “We have been saying for a long time that Russia is on the path to civil war and now we are seeing this unfold in real-time.” “But we are still focused on the frontlines,” he added. “We maximise every moment and every opportunity. This one is no exception." Soldiers on the ground told The Independent they had managed to take some streets in the east of the country and were pressing ahead Saturday afternoon. They spoke on the condition of anonymity as they are not authorised to comment to the media. “We are advancing in the Bakhmut direction, we have managed to take some streets and prisoners. And we will keep going,” said one infantryman in the east. “We had a productive night,” said another. “We can only take advantage of their confusion and seize certain parts of the front faster,” a third soldier wrote. Russian President Vladimir Putin vowed to crush what he called an "armed mutiny" after Prigozhin and his private army seized control of Rostov-on–Don Saturday early morning. The city, which is home to more than a million people, is close to the border with Ukraine and a key logistical hub for Russia’s invasion forces. Prigozhin, who has frequently lashed out Russia’s generals, vehemently denied “betraying” his country. In multiple audio messages shared online, he vowed to oust the country’s military leadership that he accused of bombing his men, rampant corruption and “lying” to Putin and to the country about their motivations behind launching a war in Ukraine. The former food vendor turned mercenary chief said he had captured the headquarters of Russia's Southern Military District after leading his forces into Russia from Ukraine. Russian officials announced an immediate state of emergency across swathes of the country and shut down roads from the south to the capital. But unverified videos later posted to Wagner’s telegram groups allegedly showed their forces already en route to Voronezh city, which lies on the main road to Moscow. They claimed Russian servicemen “lay down their arms” in Wagner's wake. Other videos shared to Telegram groups associated with Russia’s security apparatus appeared to show multiple explosions in the Voronezh region, including an oil depot on fire. “Regarding the betrayal of the motherland - [President Putin] was deeply mistaken,” Prizhochin said in his latest audio clip shared online. “We are patriots of our country, we fought and are fighting. No one is going to turn themselves in at the request of the president, the [intelligence] or anyone else,” he vowed. President Zelensky meanwhile said that “Russia’s weakness is obvious”, in comments posted to Twitter. “Everyone who chooses the path of evil destroys himself," he continued. “The longer Russia keeps its troops and mercenaries on our land, the more chaos, pain, and problems it will have for itself later.” British defence officials said that Russia was facing “the greatest challenge in recent times” Prime Minister Rishi Sunak said on Saturday urged all parties in Russia to protect civilians. Read More Rishi Sunak ‘in touch with allies’ about Wagner group rebellion in Russia Who is Yevgeny Prigozhin? 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