US President Joe Biden said on Tuesday he would consider personal sanctions on Putin if Russia invades Ukraine, as Western leaders stepped up military preparations and made plans to shield Europe from a potential energy supply shock.

Russia has massed more than 100,000 troops around Ukraine and the West fears it may invade in an attempt to annex its former Soviet republic.

Truss said Britain was already supplying support to Ukraine.

"We're supplying defensive weapons. We're providing economic support," she told Sky on Wednesday.

"We are urging Russia to desist from an incursion and we're making it very clear that if they were to do that there would be severe economic cost to Russia - severe sanctions."

Asked about possible sanctions on Putin, Truss said: "We're not ruling anything out.

"We'll be bringing forward new legislation to make our sanctions regime tougher so we are able to target more companies and individuals in Russia. We will be bringing that forward in the next few days. I'm not ruling that out."

Russia has repeatedly said it has no intention of invading Ukraine, that it can deploy troops wherever it wants on its own territory and that the West is gripped by Russophobia.

Australian Associated Press