BRITAIN has warned of mass unrest across Russia after Wagner group mercenaries seized a Russian military HQ amid fears of a coup. Putin is facing one of the biggest challenges to his iron-fist rule since he took power in the Kremlin more than two decades ago. Founder of Wagner private mercenary group Yevgeny Prigozhin and his troopsReuters AFPVladimir Putin made a rare early morning address after the rebellion[/caption] The Foreign Office said: “There are reports of military tensions in the Rostov region and a risk of further unrest across the country. “Additionally, there is a lack of available flight options to return to the UK.” The UK government continues to advise against all travel to Russia. Emmanuel Macron is also closely monitoring the situation, the French president’s office said. “The president is following the situation very closely,” the Elysee said. “We remain focused on supporting Ukraine.” Germany is also “closely following” the dramatic events in Russia. Wagner boss Yevgeny Prigozhin vowed to “punish” Russia after he blamed the Kremlin for a missile attack on a Wagner training camp in Bakhmut, Ukraine, which killed dozens. Early on Saturday, he announced he had taken control of the Russian army HQ in Rostov-on-Don – as he vowed to march toward Moscow. Prigozhin – Putin’s former pal – sensationally claimed his forces now had all military facilities in the city under their control – including the air field. Extraordinary pictures show the Russian military building surrounded by tanks and troops from the Wagner Group. A Russian security source said Wagner fighters also seized control of all military facilities in the city of Voronezh – around 310 miles south of Moscow. Fuming Putin delivered a rare early morning address on the rebellion – blasting Prigozhin’s move as “treason” and a “mortal blow” to Russia. The 70-year-old warned: “This is a criminal campaign. It is equivalent to armed mutiny. “Russia will defend itself and repel this move. We are fighting for the life and security of our citizens and our territorial integrity. “Everything has to be done in order to put this danger to rest. It is an attempt to subvert us from inside. This is treason. “In the face of those who are fighting on the front, this is a stab in the back of the troops and the people of Russia.” THIS IS A DEVELOPING STORY… The Sun is your go to destination for the best celebrity news, football news, real-life stories, jaw-dropping pictures and must-see video. Download our fantastic, new and improved free App for the best ever Sun Online experience. For iPhone click here, for Android click here. Like us on Facebook at www.facebook.com/TheSun and follow us from our main Twitter account at @TheSun.