A Labour government would have an “iron-clad commitment” to supporting Ukraine against Putin, two shadow ministers have said.
The pledge came as shadow foreign secretary David Lammy and shadow defence secretary John Healey visited the country’s capital, Kyiv.
The pair visited to discuss a “new UK plan” to help ensure victory against Russia’s “imperial invasion”.
Prime Minister Rishi Sunak said Labour would not match Tory defence spending.
In a joint statement, Mr Lammy and Mr Healey said they visited together to show a united front against Mr Putin’s attempts to divide the West.
“Moscow’s deepened cooperation with Beijing, Tehran and Pyongyang requires us to deepen our co-operation with Britain’s allies to demonstrate that our commitment to Ukraine will outlast Vladmir Putin’s imperial invasion,” they said.
“The next Labour government’s commitment to Ukraine will be ironclad, and European security will be our first foreign and defence priority.
“Labour’s action plan lays out a wide-ranging approach to stand with Ukraine, confront Russian aggression and pursue Putin for his war crimes. We will stand with Ukraine until it wins.”
The visit was intended to send a message that, should Labour win the next general election, there would be “no change in our military, diplomatic, financial and political support to Ukraine”, they said.
As Russian attacks on the Kharkiv region intensify, the Labour MPs met the head of the President’s Office Andriy Yermak and Defence Minister Rustem Umerov, to discuss what a Labour government’s priorities would be.
The plan for Ukraine sets out five priorities: fast-tracking military support, deepening diplomatic efforts, targeting Russian aggression, boosting industrial production and supporting recovery and reconstruction.
Mr Lammy and Mr Healey pledged that a Labour government would help to create “a clear path for Ukraine’s Nato membership” and called for a renewed focus on co-operation between Nato nations leading up to the Nato75 Summit in July.
The pair also set out a wide-ranging plan to back Ukraine in the long term, including action to isolate Russia.
Earlier on Monday, Mr Sunak said the UK “stands at a crossroads” ahead of “some of the most dangerous years”, in a pre-election pitch to voters.
He said Labour would not match his pledges on defence including a commitment to boost defence spending to 2.5% of national income by 2030.
Labour has said it would meet the same target when economic conditions allow.