The UK “will not waver” in its support for Ukraine, Downing Street said as Vladimir Putin accused the West of provoking the invasion he launched almost a year ago.

Rishi Sunak is under pressure to do more to aid the defence of Ukraine after predecessors Liz Truss and Boris Johnson called for fighter jets to be supplied to Kyiv.

The Prime Minister’s official spokesman said the UK was working to ensure Ukraine had the “right capabilities”, including training fighter pilots.

In Moscow, the Russian President used his state-of-the-nation address to claim Ukraine “has become hostage of the Kyiv regime and its Western masters, which have effectively occupied the country”.

He risked further inflaming tensions with the West by suspending participation in the last remaining nuclear arms control pact with the US.

The UK’s ambassador in Kyiv, Dame Melinda Simmons, said: “Nobody is responsible for the Russian invasion of Ukraine but Russia.”

The Prime Minister’s official spokesman told reporters in Westminster that Mr Sunak had not watched Mr Putin’s speech as he was chairing a Cabinet meeting, but he noted that “nearly one year on, the West’s resolve has only been strengthened and Ukraine continues to demonstrate its ability to defend its sovereignty”.

“The UK, for our part, will not waver in its support, both in the short and long term and will continue to lead the way in both providing support bilaterally but also working with our parties so we can go even further as a group of allied countries.”

In response to Ms Truss and Mr Johnson calling for jets for Ukraine, the spokesman said: “We’re working with all our partners to shore up and improve Ukraine’s air defences.

“The UK has already announced training for Ukrainian pilots on Nato-standard jets and we’re working with our partners on the next steps, ensuring they have the right capabilities that meet the requirements for fighter jets and infrastructure to defend their skies.

“So there’s a range of ways we’re already going further.”

Asked whether Mr Sunak welcomed his predecessors’ advice, the official said: “Of course, and we’ll always listen to former prime ministers.”