Vladimir Putin’s mouthpieces have blasted both Britain and the US after London and Washington warned an “imminent attack” could strike the Russian capital. The embassies said “extremists” were planning to attack large gatherings in Moscow. They also issued a warning to citizens to avoid events for the next two days. It was not clear who is believed to have been plotting the attacks. However, people have been told to avoid crowds, be aware of their surroundings and monitor local media for updates. The UK and US also advised respective nationals against all travel to Russia. Several concerts are…