UK political leaders have marked the second anniversary of the war in Ukraine by vowing to stand with Kyiv “until they prevail”.

Prime Minister Rishi Sunak said “tyranny will never triumph” as President Volodymyr Zelensky’s troops defend the country against an emboldened Russia.

Mr Sunak said the UK is “going further in our support”, and Britain is prepared to do “whatever it takes, for as long as it takes”.

Saturday marks two years since the Kremlin launched its attack on Ukraine, starting the biggest incursion in a European country since the Second World War.

We are prepared to do whatever it takes, for as long as it takes, until they prevail

Mr Sunak, who visited Kyiv last month to sign a new security agreement and announce an increase in military funding for the country, said on Friday: “When (Russian President Vladimir) Putin launched his illegal invasion two years ago, the free world was united in its response.

“We stood together behind Ukraine. And on this grim anniversary, we must renew our determination.

“I was in Kyiv just a few weeks ago and I met wounded Ukrainian soldiers. Each harrowing story was a reminder of Ukraine’s courage in the face of terrible suffering.

“It was a reminder of the price they are paying not only to defend their country against a completely unjustified invasion, but also to defend the very principles of freedom, sovereignty and the rule of law on which we all depend.”

He added: “This is the moment to show that tyranny will never triumph and to say once again that we will stand with Ukraine today and tomorrow.

The UK and our allies will stand in solidarity with them until their day of victory

“We are prepared to do whatever it takes, for as long as it takes, until they prevail.”

Labour leader Sir Keir Starmer, who hopes to enter Number 10 after the general election this year, said Britain would always support Ukraine “no matter who is in power in this country” and said Mr Putin’s “cowardice and barbarity” will not prevail.

Sir Keir said: “The resistance of the Ukrainian people has inspired and humbled the world. The UK and our allies will stand in solidarity with them until their day of victory.

“We will not waver. We will not abandon them. We will not be divided in the face of tyranny or oppression.

“We look together to the day when Ukraine secures justice and liberty in their rightful homeland, when Ukrainians can return home and rebuild their great country, and live peacefully, freely and proudly.”

European countries are struggling to find enough stock to send to Kyiv, and US help worth 60 billion US dollars (£47 billon) is stalled over political differences in Washington.

Ukrainian forces withdrew from the strategic eastern city of Avdiivka at the weekend, where they had battled a fierce Russian assault for four months despite being heavily outnumbered and outgunned.

Kyiv has kept up strikes behind the 930-mile front line but moved to a defensive posture amid critical shortages on the battlefield.