The Foreign Secretary has met with Volodymyr Zelensky to discuss how best the UK can continue to support Ukraine, on and off the battlefield.
James Cleverly and the Ukrainian President met in the war-torn nation's capital Kyiv amid signs Ukraine's counter-offensive against the Russian invasion may have begun.
Mr Cleverly reassured Mr Zelensky and Ukrainian Foreign Minister Dmytro Kuleba of battlefield support, as well as banking guarantees and other methods of aid, the Foreign, Commonwealth and Development Office (FCDO) said.
It comes as Britain gets ready to host a conference focused on Ukraine’s economic recovery, later this month.
In a video posted to Mr Zelensky's Facebook page, Mr Cleverly is heard saying that the UK "will continue backing you and your country until you are victorious".
The Ukrainian President thanks the UK for the "big support" it has given his country.
He wrote on Facebook: "During the meeting, we discussed important topical issues: Ukraine's expectations from the Nato Summit in Vilnius, promotion of the Ukrainian peace formula and preparation of the global summit on its implementation, as well as the London international conference on the reconstruction of Ukraine.
"We are very grateful for the support that the UK has provided and continues to provide to Ukraine."
Ukraine has long called to become a Nato member, but allies are divided on when and how any accession might happen as the Ukrainian conflict continues.
Prime Minister Rishi Sunak last week said Ukraine's "rightful place" is in Nato, at a gathering of European leaders in Moldova ahead of the key meeting of Nato leaders in Lithuania in July.
In the video from Kyiv, the Foreign Secretary is seen speaking of his previous visit to Ukraine last November when it was "cold and it was dark".
"But this time I can see there's more life in the city. The traffic is heavier, which normally is a bad sign in a city. But I think for me it demonstrates what I mean to be true.
"And that is that the Ukrainian people are not going to allow themselves to be broken by this."
He added: "The sunshine and the leaves and the flowers shouldn't distract us from the fact that there is still very much work to be done."
Has Ukraine's counter-offensive already begun?
Russia claims to have foiled a major Ukrainian offensive in Donetsk, with a grainy video apparently the evidence.
The Russian defence ministry said the country's troops thwarted a Ukrainian offensive, killing hundreds of troops and destroying multiple armoured vehicles in the process.
Ukraine has refuted the claims, accusing Russia of spreading lies, while experts believe this claimed offensive is a sign that "something has begun".