There have been numerous reports that Russian President Vladimir Putin's presidential plane took off from Moscow's Vnukovo airport and then headed north-west, media reports said.
According to data from the FlightRadar tracking website, the plane reached the Tver area - about 110 miles from Moscow and where Putin has a residence - before disappearing from the system, The Guardian reported.
It has not been possible to confirm whether Putin was on the plane and his spokesperson, Dmitry Peskov, has told the Tass news agency the President is "working in the Kremlin".
Meanwhile, Iranian state media quoted Foreign Ministry spokesperson Nasser Kanaani on Saturday as saying Iran supports the rule of law in the Russian Federation and considers the latest developments there an internal Russian matter.
The simmering conflict between Moscow's military leadership and Yevgeny Prigozhin, the bombastic chief of private mercenary group Wagner, has exploded into an open insurrection that plunges Russia into renewed uncertainty and the very real threat of civil war, CNN reported.
Prigozhin unleashed a new tirade against the Russian military on Friday and then marched his troops into the Russian city of Rostov-on-Don, which fell into hands by noon.
The Russian Wagner mercenary group on Saturday claimed to have seized military facilities in the cities of Rostov and Voronezh, despite President Vladimir Putin's order to neutralise the mercenaries.
In a social media post, the group's chief Yevgeny Prigozhin said that he was in Rostov-on-Don, in southern Russia close to the Ukraine border, and that his forces have control of military facilities and the airfield, reports CNN.
He pledged to blockade Rostov and move on to Moscow if Russian Defence Minister Sergei Shoigu and top general Valery Gerasimov did not meet him in the city, where Russia's Southern Military District is headquartered.
The Wagner group also claimed that said it had taken control of Russian military facilities in the second city of Voronezh, saying "the army switches to the side of the people".
Earlier, the Governor of Voronezh oblast said that "a convoy of military equipment is moving along the M-4 Don Federal Highway", which connects the city and Rostov-on-Don.
Voronezh is directly north of the Rostov region.
The simmering tensions come after Prigozhin announced that his fighters were entering the Rostov region and that Russian Guards and military police have joined the Wagner group.
Videos circulating on social media and geolocated to Rostov city show military vehicles on the streets and helicopters over the city Saturday morning.
In response to the developments, President Putin said in a televised address to the nation: "Any internal turmoil is a deadly threat to our statehood, to us as a nation. This is a blow to Russia, to our people. And our actions to protect the motherland from such a threat will be tough.
"All those who deliberately embarked on the path of betrayal, who prepared an armed rebellion, who embarked on the path of blackmail and terrorist methods, will suffer inevitable punishment and answer both before the law and before our people.
"I urge those who are being dragged into this crime not to make a fatal and tragic mistake, but to make the only right choice -- to stop participating in criminal acts."
Moscow announces Anti-terrorism Committee
On Saturday morning, Russia's National Anti-terrorism Committee announced that a counter-terrorist operation regime has been introduced in Moscow, the region and the Voronezh to prevent possible terrorist acts.
On Friday night, the Kremlin ordered the arrest of Wagner chief Yevgeny Prigozhin after Russian intelligence accused him of calling for an "armed rebellion".
Late Friday night, the Federal Security Service (FSB) urged Wagner mercenaries to "stop the columns" and detain their leader after the latter vowed retaliation over the Russian military allegedly killing a "huge amount" of Wagner fighters during a strike on a camp earlier in the day, reports CNN.
Russian state TV also interrupted programming Friday night to report a Defence Ministry statement claiming Prigozhin's comments "did not correspond to reality" and demanded him to halt "illegal actions".
Prigozhin's claims
Earlier on Friday, Prigozhin had claimed that his forces crossed the border into Russia from Ukraine, but did not give any proof to back his allegation.
"Many dozens, tens of thousands of lives, of Russian soldiers will be punished. I ask that nobody put up any resistance."
He also said the "evil" in the Russian military leadership must be stopped and vowed to "march for justice", but the Wagner chief clarified that he was not attempting a military coup.
Putin's address
Putin called Wagner's actions "treason" and has vowed to punish those behind the "armed uprising", CNN reported. He is facing the most serious threat to his hold on power in all the 23 years he's run the nuclear state, media reports said.
And it is staggering to behold the veneer of total control he has maintained all that time - the ultimate selling point of his autocracy - crumble overnight, CNN reported.
The opening salvos of Wagner chief Yevgeny Prigozhin's disobedience were at times assessed as a feint - a bid by Putin to keep his generals on edge with a loyal henchman as their outspoken critic. But with Putin forced to admit that Rostov-on-Don, his main military hub, is out of his control puts paid to any idea that this was managed by the Kremlin. It is likely however Wagner's units have planned some of this for a while.
Spontaneous mutiny?
The justification for this rebellion appeared urgent and spontaneous - an apparent air strike on a Wagner camp in the forest, which the Russian Ministry of Defence has denied - appeared hours after a dissection of the rationale behind the war by Prigozhin, CNN reported.
He partially spoke the truth about the war's disastrous beginnings: Russia was not under threat from NATO attack, and Russians were not being persecuted. The one deceit he maintained was to suggest Russia's top brass was behind the invasion plan, and not Putin himself. Wagner's forces have pulled themselves together very fast and moved quickly into Rostov. That's hard to do spontaneously in one afternoon, CNN reported.
Perhaps Prigozhin dreamt he could push Putin into a change at the top of a ministry of defence the Wagner chief has publicly berated for months. But Putin's address on Saturday morning has eradicated that prospect.
This is now an existential choice for Russia's elite - between the president's faltering regime, and the dark, mercenary Frankenstein it created to do its dirty work, which has turned on its masters, as per CNN.
It is a moment of clarity for Russia's military too. A few years ago, Prigozhin's mild critiques would have led to elite special forces in balaclavas walking him away. But now he roams freely, with his sights openly on marching to Moscow.
This is not the first time this spring Moscow has looked weak. The drone attack on the Kremlin in May must have caused the elite around Putin to question how on earth the capital's defences were so weak.
Days later, elite country houses were targeted by yet more Ukrainian drones. Among the Russian rich, Friday's events will remove any question about whether they should doubt Putin's grip on power, CNN reported.
(With inputs from IANS)
