King Charles III on Wednesday led commemorations to mark the 80th anniversary for the World War II D-Day landings, joining British veterans, other senior royals and political leaders.

The 75-year-old monarch, who only recently resumed public engagements as he battles cancer, spoke at a remembrance event in Portsmouth, on Englands south coast, organised by the Ministry of Defence.

Allied troops began departing from the port city and other sites on the southern English coast on June 5, 1944, crossing the Channel and battling to land the next morning on beaches in northern France.

As we give thanks for all those who gave so much to win the victory whose fruits we still enjoy to this day, let us once again commit ourselves always to remember, cherish and honour those who served that day, Charles told the flag-waving audience.

As head of state, Charles is commander-in-chief of Britains armed forces and served himself in the Royal Navy and Royal Air Force.

He and his wife Queen Camilla will be in France on Thursday for further commemorations.

Senior royals, Prime Minister Rishi Sunak and WWII veterans will join dozens of heads of state including US President Joe Biden, French leader Emmanuel Macron and other dignitaries at services across Normandy.

It will be Charless first overseas visit since his cancer diagnosis was announced in February.

˜Lucky

Wednesdays UK commemorations, which included readings, music and reenactments from the period also featured recollections from D-Day veterans, mainly in pre-recorded videos.

However, Roy Hayward - who was aged 19 at the time - took to the stage to speak of his emotions eight decades on.

I always considered myself one of the lucky ones that survived, because so many of us didnt, said the veteran, who later in WWII lost both his legs below the knees to amputation.

I represent the men and women who put their lives on hold to go and fight for democracy and this country.

Im here to honour their memory and their legacy, and to ensure that their story is never forgotten, Hayward added.

Charless elder son and heir Prince William - an RAF search and rescue pilot before becoming a full-time royal - also addressed the assembled dignitaries.

Today, we remember the bravery of those who crossed the sea to liberate Europe, those who waited for their safe return, he said after reading aloud an extract from a veterans diary.

The leaders of some of Britains main political parties took a break from general election campaigning ahead of the countrys July 4 poll.

Sunak penned a message in the event programme and read out a message that was delivered to all D-Day troops.

Labour opposition leader Keir Starmer looked on from the audience.

Just hours earlier, the political rivals were clashing fiercely in the first live TV debate of the election campaign. (AFP)

Britains King Charles III meets D-Day veteran Eric Bateman and members of his family, following the UKs national commemorative event to mark the 80th anniversary commemorations of Allied amphibious landing