Sir Keir Starmer will attend his first meeting of the British-Irish Council, which is being hosted in Edinburgh today.
The prime minister is set to hold talks with Scottish first minister John Swinney, Irish Taoiseach Simon Harris, Welsh first minister Eluned Morgan and Northern Irish first minister Michelle O'Neill.
The 42nd summit is expected to focus on the climate crisis and transitioning to clean energy, whilst also marking the 25th anniversary of the first meeting.
First Minister John Swinney said: “The meeting in Edinburgh provides a forum for us to discuss the greatest challenge facing the next 25 years - that of climate change and delivering a just transition.
“As First Minister of Scotland, achieving a just transition is integral to the four main priorities of my government.
"Scotland needs to attract investment to tackle climate change and grasp the opportunities of that journey to net zero in a way that grows our economy and helps provide investment to tackle child poverty and improve public services.”
Improving household finances and a transition to clean energy is among Mr Starmer's six government priorities.
He has vowed to work constructively with devolved parliaments since entering No 10 in July.