Andy Burnham will hand Ukraine the blueprints to produce long-range missiles ahead of his visit to Kyiv.
The Prime Minister is set to announce that he will allow European defence firm MBDA to declassify information on UK components for the long-range Scalp missile during his first foreign trip to Ukraine.
The Scalp missile - the French-manufactured version of Britain's Storm Shadow - uses shared French and British technology.
Kyiv and Paris are looking to set up assembly lines to produce the missile within Ukraine.
Mr Burnham is visiting Kyiv to mark Ukraine's independence day and signal the UK’s continued support for the country under his administration.
He will also participate in a number of Independence Day events and accept an award on behalf of the British people recognising the UK's support.
Arriving this morning, the Prime Minister will chair a meeting of the so-called coalition of the willing, set up by the UK and France to support Ukraine under Sir Keir Starmer.
In the UK, the Ministry of Defence has marked the occasion by illuminating its main building and the Palace of Westminster with the colours of the Ukrainian flag.
Mr Burnham said: "On Ukraine’s 35th anniversary of independence, the Ukrainian people should be in no doubt: the UK is behind you today and for as long as it takes.
"I am proud of the contribution our country has made to Ukraine and I want the Ukrainian people to hear it directly from me that our support will not waver. After all, Ukraine's security is our security."
"The friendship between our two countries will long outlast Russia’s illegal war. In both the fight and in the rebuilding to come, we will stand with Ukraine and deliver opportunities for people across both our countries.
"Russia should be in no doubt of our resolve. We will not back down until there is a just and lasting peace."
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The Prime Minister welcomed Ukrainian President Volodymyr Zelenksy - his first international visitor - just days after entering No10, saying at the time that Britain would "honour every commitment this country has made to Ukraine in full".
The meeting of the coalition of the willing, which comprises 34 countries have promised to help secure Ukraine in the event of a peace deal with Russia, will be chaired by Mr Burnham and French President Emmanuel Macron, who will join remotely by video link.
Mr Macron reaffirmed his support of Kyiv on social media on Saturday, saying it was "crucial to provide Ukraine with all the necessary means to defend its skies and thwart this aggression".
"Russia seeks to break Ukraine through terror: it will not succeed," he added. "United alongside Ukraine, we will ensure that law and justice prevail over force."
Last week, Russia threatened nuclear strikes on Britain, accusing the Government of deliberately escalating the Ukraine war after it emerged British-built drones were used to strike industrial targets.
"London's actions will inevitably carry consequences for which it will have to answer," Russia said in a statement issued by its embassy.
"The deeper its involvement in the conflict and the greater its support for Kyiv’s terrorist machinery, the higher the price it will pay."
And just days later, Russia pulled its ambassador from London as fears of a total diplomatic collapse between No10 and the Kremlin have heightened.
Withdrawing an ambassador is recognised as a way for a state to register serious displeasure without fully severing ties.
A senior diplomatic source told The Times the breakdown in communication was concerning, adding that communication was the "only tool" to avoid catastrophic scenarios on the global stage.
Mr Zelensky, meanwhile, faces a rebellion from former defence minister Mykhailo Fedorov, who called for elections to be held despite despite the ongoing war with Russia, which has waged since 2022.
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