Russia on Wednesday conducted its first major nuclear drills since the start of its war on Ukraine and President Vladimir Putin made unfounded claims that Kyiv was seeking to develop a “dirty bomb”, as Moscow continued to ramp up the rhetoric over possible nuclear use in the conflict.

Putin monitored events via videoconference from the Kremlin as Russia’s military practised what his defence minister Sergei Shoigu called a “mass nuclear strike with strategic attack forces in response to a nuclear attack by our adversary”.

Addressing security services chiefs from a group of former Soviet countries after the drills, Putin said “global geopolitical confrontation has sharply increased” and accused the US of using Ukraine as a “battering ram” against Russia.