President Vladimir Putin has ordered Russian nuclear deterrent forces put on high alert Sunday amid tensions with the West over his invasion of Ukraine.

At a meeting with his top officials, the president ordered the defense minister and the chief of the military’s general staff to put the nuclear deterrent forces in a “special regime of combat duty”.

"I order the defense minister and the chief of the general staff of the Russian armed forces to put the deterrence forces of the Russian army into a special mode of combat service," Putin said in a televised address.

"As you can see, not only do Western countries take unfriendly measures against our country in the economic dimension - I mean the illegal sanctions that everyone knows about very well - but also the top officials of leading NATO countries allow themselves to make aggressive statements with regards to our country," he added.

The president said aggressive statements by NATO leaders and economic sanctions against Moscow were behind the decision.

The order will heighten fears across the West that Russian forces could use nuclear weapons in the conflict with Ukraine.