The Russian military says its nuclear deterrent forces have been put on high alert in line with President Vladimir Putin’s order.

Russia’s defence minister Sergei Shoigu has reported to Mr Putin that command posts of all of Russia’s nuclear forces have been boosted with additional personnel.

The Russian defence ministry said that the high alert status applies to all components of Russian nuclear forces, the strategic missile forces that oversee land-based intercontinental ballistic missiles, the Northern and Pacific Fleets that have submarine-launched intercontinental ballistic missiles, and the long-range aviation that has a fleet of nuclear-capable strategic bombers.

Mr Putin ordered Russia’s nuclear forces to be put on high alert Sunday, citing Western sanctions and “aggressive statements” by Nato powers.

It is not immediately clear what specific steps the measure implies, but it has raised fears that the war in Ukraine could lead to a bigger and even more dangerous confrontation.