The new British King Charles III pledged to serve his nation in his first address as he paid tribute to his late mother, Queen Elizabeth II.

"Throughout her life, her majesty the queen – my beloved mother – was an inspiration and example to me and to all my family, and we owe her the most heartfelt debt any family can owe to their mother," he said.

The king said his mother pledged to devote her life "to the service of her peoples" on her 21st birthday in 1947.

He said: "That was more than a promise: it was a profound personal commitment which defined her whole life."

"She made sacrifices for duty," the king added.

"Her dedication and devotion as sovereign never waivered, through times of change and progress, through times of joy and celebration, and through times of sadness and loss."

"As the queen herself did with such unswerving devotion, I too now solemnly pledge myself, throughout the remaining time God grants me, to uphold the constitutional principles at the heart of our nation," he said.

The king said he was creating his son and heir, William, Prince of Wales adding: "With Catherine beside him, our new Prince and Princess of Wales will, I know, continue to inspire and lead our national conversations, helping to bring the marginal to the centre ground where vital help can be given."

The king said, "My life will of course change as I take up my new responsibilities."

He added: "It will no longer be possible for me to give so much of my time and energies to the charities and issues for which I care so deeply. But I know this important work will go on in the trusted hands of others."

King Charles also expressed his love for Prince Harry and Meghan, his son and daughter-in-law, a significant gesture toward a couple whose relationships with the rest of the family have been strained.

"I want also to express my love for Harry and Meghan as they continue to build their lives overseas," Charles said.