MOSCOW - The head of the Wagner mercenary group Yevgeny Prigozhin announced on Saturday that he was inside the army HQ in southern Russia’s Rostov-on-Don and that his fighters control the city’s military sites, including an aerodrome.

This, hours after he had revealed that his Wagner fighters had crossed the border into Russia from Ukraine and were prepared to go “all the way” against Moscow’s military.

“We are inside the (army) headquarters, it is 7.30am (12.30pm Singapore time),” Prigozhin said in a video on Telegram. “Military sites in Rostov, including an aerodrome, are under control,” he added.

Russia’s military headquarters in Rostov-on-Don are a key logistical base for its offensive in Ukraine.

Prigozhin said that planes taking part in the Ukraine offensive “are leaving as normal” from the airfield. “We took (the aerodrome) under control so that the attack aviation did not strike us, but strike Ukrainians,” he added.

He called on Russians not to believe what they were being told on state television.

“A huge amount of territory is lost. Soldiers have been killed, three, four times more than what it says in documents shown to the top (leadership).”

In the video from Rostov, he claimed Russia’s chief of General Staff Valery Gerasimov “ran away from here when he found out that we are approaching the building”.

He has vowed to topple Mr Gerasimov and Defence Minister Sergei Shoigu.

A Wagner-linked Telegram channel on Saturday published another video of what it said was Prigozhin talking with two army officials in the Rostov headquarters.

Holding a rifle on his knees and wearing a cap with the Russian flag on it, the Wagner chief said: “We came here to get the chief of General Staff (Gerasimov) and Shoigu.”

“Until then, we will be here, block the city of Rostov and go on to Moscow.”

The Kremlin, which had on Friday accused the Wagner chief of armed mutiny, said that President Vladimir Putin would “soon” address the nation.

In an earlier audio message on the platform, Prigozhin had vowed: “We are going onwards and we will go to the end.”

“We will destroy everything that stands in our way,” he added in the most audacious challenge to Mr Putin since the start of the Russian offensive in Ukraine last year.

He warned Russians against resisting his forces and called on them to join him, adding “there are 25,000 of us”.

“We need to put an end to this mess,” he said, adding, “this is not a military coup, but a march of justice”.

On Saturday, the governor of the Lipetsk region in central Russia, Igor Artamonov, said that the M-4 motorway connecting Moscow with southern regions was closed to traffic at the border with the Voronezh region, some 400km south of Moscow.

This, after Prigozhin appeared to have sent an armed convoy of his Wagner fighters on the 1,200km drive towards Moscow.

As a long-running standoff between Prigozhin and the military top brass appeared to come to a head, Russia’s FSB security service opened a criminal case against him, Tass news agency said. It called on the Wagner private military company forces to ignore his orders and arrest him.

Prigozhin earlier said, without providing evidence, that Russia’s military leadership had killed a huge number of his fighters in an air strike and vowed to punish them.

He insisted his actions were not a military coup. But in a frenzied series of audio messages, in which the sound of his voice sometimes varied and could not be independently verified, he appeared to suggest that his 25,000-strong militia was en route to oust the leadership of the defence ministry in Moscow.

He also announced that his forces had shot down a Russian military helicopter. “A helicopter has just now opened fire at a civilian column. It has been shot down by units of PMC Wagner,” he said in a new audio message.

Russian President Vladimir Putin was getting around-the-clock updates, Tass said.

Prigozhin’s warning prompted Russian authorities to tighten security measures in several regions.

“A decision has been taken to reinforce security measures in the region,” said Lipetsk Governor Artamonov. “I ask everyone to remain calm.”

In the southern region of Rostov, officials asked residents to stay home.

“Law enforcement agencies are doing everything necessary to ensure the safety of residents,” Rostov Governor Vasily Golubev said on social media. “I ask everyone to stay calm,” he said, urging locals to stay home.

Tass reported that Moscow authorities had instituted tighter security measures, and local media published amateur footage showing armoured vehicles deploying throughout the capital, including near the defence ministry.

Moscow Mayor Sergei Sobyanin said that anti-terrorist measures were being taken in the Russian capital, including additional checks on roads, to reinforce security.

The government said on its Telegram channel that the situation was under control and that measures were being taken to ensure public safety.

The deputy commander of Russia’s Ukraine campaign, General Sergei Surovikin, told Wagner fighters to obey Mr Putin, accept Moscow’s commanders and return to their bases. He said political deterioration would play into the hands of Russia’s enemies.

“I urge you to stop,” Mr Surovikin said in a video posted on Telegram, his right hand resting on a rifle.

Army Lieutenant-General Vladimir Alekseyev issued a video appeal in which he asked Prigozhin to reconsider his actions. “Only the president has the right to appoint the top leadership of the armed forces, and you are trying to encroach on his authority,” he said.

The standoff between Wagner and Moscow, many of the details of which remained unclear, looked like the biggest domestic crisis Mr Putin has faced since he sent thousands of troops into Ukraine in February last year.

Anti-Kremlin figure Mikhail Khodorkovsky urged Russians to support the Wagner chief in his bid to bring down Moscow’s military leadership.

“We need to help now, and then, if necessary, we will fight this one, too,” Mr Khodorkovsky, a former oil tycoon who fell foul of the Kremlin, wrote on social media.

He said it was important to back “even the devil” if he decided to take on the Kremlin. “And yes, this is just the beginning.”

In Washington, the White House said it is monitoring the situation and will be consulting allies and partners on developments, National Security Council spokesperson Adam Hodge said on Friday. REUTERS, AFP