Russia is prepared to launch a wave of cyber attacks on Britain that could “turn out the lights for millions”, a Cabinet minister will warn at a Nato conference on Monday.

Vladimir Putin is willing and capable of triggering a “destabilising and debilitating” electronic strike on the UK, Pat McFadden will say.

Russia is “exceptionally aggressive and reckless in the cyber realm” and wants to gain a “strategic advantage and degrade the states that support Ukraine”, Mr McFadden, who oversees policy on national security and state threats, will warn.

The Chancellor of the Duchy of Lancaster will say there is an imminent risk of a Russian cyber attack on British infrastructure and businesses that could “shut down the power grids” and deal a hammer blow to the economy.