King Charles III and Camilla look at floral tributes left outside Buckingham Palace in London. AP
Britain's King Charles pledged to give lifelong service to the people of the United Kingdom and his other realms in a solemn address to the nation a day after the death of his mother Queen Elizabeth.
"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," the king said.
"And wherever you may live in the United Kingdom, or in the realms and territories across the world, and whatever may be your background or beliefs, I shall endeavour to serve you with loyalty, respect and love, as I have throughout my life."
King Charles expressed his love for Prince Harry and Meghan, his son and daughter-in-law, during his first address as monarch on Friday, a significant gesture towards 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 in a solemn televised speech.
Earlier in the day, King Charles III shook hands with dozens of members of the public outside Buckingham Palace on Friday, as emotional supporters took photos and greeted the new monarch after the death of his mother, Queen Elizabeth, on Thursday.
Charles and his wife Camilla, Queen Consort, exit the royal carriage just outside the gates of Buckingham Palace in an unexpected move on the way back to London from Balmoral Castle in Scotland, where the Queen died.
The couple, dressed in black, were greeted to cheers and applause from a crowd of hundreds gathered outside the building, TV footage showed.
The king then shook hands with dozens of supporters and watched the floral tributes to his mother for more than ten minutes.
Several spectators sang "God save the King" and one shouted "I love you Charles! One woman kissed Charles' hand, while another reached over the guardrail to hug him and kiss him on the cheek.
Many told him they were sorry for his loss and he thanked them.
People gathered outside the building pointed their phone cameras at Charles as he walked by, flanked by security personnel.
A security guard asked people to put down their phones as the king approached and just enjoy the moment.
Charles and Camilla then walked through the palace gates.