Prime Minister Rishi Sunak has agreed to deliver a squadron of tanks to Ukraine to aid the country's efforts in re-taking territory lost to Russian forces.
Four British Army Challenger 2 main battle tanks will reportedly be sent to eastern Europe immediately, with eight more to follow shortly afterwards.
Prime Minister Rishi Sunak confirmed the UK will provide Challenger 2 tanks to Ukraine during a call with President Volodymyr Zelensky, Number 10 said.
According to Downing Street, the leaders reflected on the current state of the war in Ukraine during the phone call, with successive Ukrainian victories pushing Russia troops back and compounding their issues.
Both leaders agreed they needed to seize the moment with "an acceleration of global military and diplomatic support to Ukraine".
This included sending not only the provision of Challenger 2 tanks, but additional artillery systems.
Mr Sunak and Mr Zelensky also welcomed other similair international commitments, such as Poland's move to send Leopard 2 tanks to Ukraine.
The Prime Minister also stressed that he and the whole UK Government would work intensively with international partners to quickly support Ukraine, allow them to press their advantage and win the war.
The move would make the UK the first Western power to supply the Ukrainians with main battle tanks.
In response to the news, Shadow Defence Secretary John Healey said the Government has "Labour's fullest backing or military assistance to Ukraine" but must "set out a plan for military, economic and diplomatic support through 2023 and beyond".
"As the first anniversary of Russia's invasion approaches, this will help reassure Ukrainians that Britain will stand with them for as long as it takes and signal to Putin that things will get worse not better for Russia," he said.
Earlier this week, Western officials warned Ukraine would not be able to take back significant territory from Russia without an increase in fighting power – including tanks and other heavy armour.
There have been concerns within Nato that supplying tanks could be regarded by the Russians as a further escalation of the conflict.
However, Poland has agreed to send German-made Leopard 2 tanks to Ukraine as part of a larger international coalition.
It comes after the US promised 50 Bradley tank-killing armoured vehicles in its biggest military assistance package to date for Ukraine.
Germany also announced it would supply around 40 Marder armoured personnel carriers and France promised wheeled AMX-10 RC tank destroyers.
The Ministry of Defence (MOD) and Downing Street have been contacted for comment.