Sir Keir Starmer is in Paris to mark Armistice Day, while events will take place across the UK to commemorate the end of the First World War.
The Prime Minister met French President Emmanuel Macron as he became the first British premier to attend the armistice ceremony in Paris since Winston Churchill.
In the UK, events will focus on the National Memorial Arboretum in Staffordshire.
The Duchess of Edinburgh will be among the guests at the event.
Sir Keir’s trip to Paris comes as European leaders consider how to respond to the election of Donald Trump in the US.
The Prime Minister had already hoped to “reset” relations with Europe, and the prospect of a second Trump presidency is causing leaders on the continent to discuss what the new US administration will mean for trade and security.
As well as his talks with Mr Macron and French prime minister Michel Barnier, Sir Keir had a breakfast reception with representatives of the British defence community in France.
According to Number 10, Sir Keir is the first UK prime minister to have attended the Paris commemorations since Churchill joined General Charles de Gaulle in 1944.
It comes as Sir Keir announced more than £10 million to mark the 80th anniversary of VE Day and VJ day.
The Prime Minister has pledged a “moment of national reflection” in 2025, with events on May 8 to commemorate the 80th anniversary of the allied victory in Europe, and also on August 15 to mark the end of the Second World War.
Sir Keir said he is “honoured to be in Paris to stand united with President Macron in tribute to the fallen of the First World War who made the ultimate sacrifice for the freedom we enjoy today”.
He added: “These events are vital in ensuring the memory of millions of young soldiers, sailors, and aviators live on for generations to come.
“That is why this Government will bring the nation together in a moment of national reflection to mark the 80th anniversaries of VE and VJ Day next year, delivering on our commitment to strengthen community spirit and cohesion and remember the fallen.”
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