The leader of the Wagner private military company, Yevgeny Prigozhin, announced on Saturday that he had entered Russia with his troops to overthrow the country’s military command.

He said he and his 25,000 soldiers were willing to sacrifice their lives.“We are all prepared to give our lives.

All of us, 25,000, and then another 25,000,” the 62-year-old Prigozhin said in a voice message, after accusing the Russian military leaders of attacking his forces.“We are laying down our lives for the Russian people.”The Russian authorities reacted by increasing security in several regions and the Moscow mayor said that “anti-terrorism” actions were being taken in the city.The FSB security service blamed Prigozhin for trying to start a “civil conflict” and called on Wagner fighters to capture him.Here are the latest developments:'All military sites of Rostov under our control'Wagner chief said 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, after vowing to bring down Moscow's top brass."We are inside the (army) headquarters, it is 7:30 am (0430 GMT)," Prigozhin said in a video on Telegram.

"Military sites in Rostov, including an aerodrome, are under control," he said.Russia tightens security on route to MoscowThe Kremlin was taking no chances.

Authorities tightened security in the capital, including around government buildings, and put riot police on alert, Tass said.

In Moscow, critical facilities were "under reinforced protection", the TASS state-run news agency reported, citing a law enforcement source.

Early Saturday, Moscow’s mayor said city authorities were conducting unspecified “anti-terrorist actions.” Regulators also blocked access to Google’s news aggregator on major platforms in Russia, according to NetBlocks, an Internet-monitoring group.Biggest challenge for Putin since Ukraine invasionThe dramatic turn of events, with many details unclear, looked like the biggest domestic crisis President Vladimir Putin has faced since he ordered a full-scale invasion of Ukraine - something he called a "special military operation" - in February last year.President Vladimir Putin was getting round-the-clock updates from security officials on their efforts to counter “the attempt at an armed mutiny” by Yevgeny Prigozhin, Tass reported early Saturday morning in Moscow, citing Kremlin spokesman Dmitry Peskov.Putin had long appeared to tolerate the mercenary’s outbursts, relying on his troops to fight in key parts of the front.

But his high profile rankled with the military brass, which regularly sought to undermine and sideline him.Why Wagner chief may have rebelledPrigozhin, whose Wagner militia spearheaded the capture of the Ukrainian city of Bakhmut last month, has for months been openly accusing defence minister Sergei Shoigu and Russia's top general, Valery Gerasimov, of rank incompetence and of denying Wagner ammunition and support in its battles in Ukraine.As their feud appeared to come to a head, the ministry issued a statement saying Prigozhin's accusations were "not true and are an informational provocation".Prigozhin said 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 25,000 fighters were en route to oust the leaders of the defence establishment in Moscow.Though he threatened to destroy “anyone who will try to resist,” Prigozhin said “this is not a military coup.

This is a march of justice.”On Friday, Prigozhin posted a video on Telegram accusing the defense ministry of “deceiving” Russians and Putin about the war as he challenged Kremlin justifications for the February 2022 invasion of Ukraine.The mercenary leader has increasingly put himself at odds with the Kremlin narrative about the war, while warning Russians that full mobilization and martial law are necessary to avoid defeat in Ukraine.In an interview with a local journalist last month, he heaped praise on the performance of Ukraine’s military and scorned the “denazification and demilitarization” goals that Putin and top Kremlin officials used as justification for the war.

“How did we demilitarize it? We actually militarized it,” he said.

“It’s now one of the strongest armies.”He also accused Russia’s top defense officials of using the war to enrich themselves and leaving the country unprotected following a border incursion by attackers who crossed from Ukraine.End of Wagner?While it’s not certain yet whether Prigozhin will follow through on his threats, said Tatyana Stanovaya, founder of R Politik, a political consulting firm, “the authorities’ reaction is clear - they’re putting down the mutiny.”“In my view, this is the end of Wagner,” she said.

“The system can’t tolerate his activeness any longer.”Biden briefed on Russian situationIn Washington, President Joe Biden has been briefed on the situation while the top two members of the Senate Intelligence said “we are closely monitoring what appears to be a significant internal conflict among Russian forces.”(With inputs from agencies)