Watch a view of Moscow city centre on Saturday 24 June after Vladimir Putin has vowed to crush an “armed mutiny” from the Wagner mercenary group.
The rebellion marks “the most significant challenge to the Russian state” in recent times, according to UK defence officials.
Mr Putin, the president of Russia, called the actions of the private military company a “betrayal” after its chief Yevgeny Prigozhin vowed to topple Moscow’s military leadership.
“Over the coming hours, the loyalty of Russia’s security forces, and especially the Russian National Guard, will be key to how the crisis plays out. This represents the most significant challenge to the Russian state in recent times,” the UK’s Ministry of Defence tweeted.
Mr Putin, meanwhile, has promised to “defend the people” and Russia.
He addressed the nation on Saturday morning after Mr Prigozhin claimed that his forces now control military facilities in Russia’s southern city Rostov-on-Don.