Justin Trudeau is in the U.K. to pay his respects to the late Queen Elizabeth II and welcome Canada's new monarch, King Charles III.

On Saturday, September 17, the PM posted a picture of himself and his wife, Sophie Grégoire Trudeau, on his Instagram, where he can be seen writing in a book with a portrait of the late queen nearby.

"Her Majesty Queen Elizabeth II served for her entire life, and bore the weight of her duties with impeccable grace," he captioned his post.

"Sophie and I are in London for Her Majesty’s funeral – and today, we marked the solemn occasion by signing the book of condolences."

A video posted on The Royal Family Channel's YouTube account shows Trudeau and the prime ministers of other countries meeting briefly with King Charles III.

In the clip, Trudeau can be seen shaking hands with the new king and sharing some brief words before sitting down.

As well, Prime Ministers Anthony Albanese of Australia, Philip Davis of Bahamas, Andrew Holness of Jamaica, and Jacinda Ardern of New Zealand also pay their respects in the video.

On September 10, Trudeau gave a speech in support of the monarch.

"We have no doubt that his deeply felt commitment to education, the environment, and the empowerment of young people will provide a strong foundation from which he will continue to work toward the betterment of the commonwealth and its people," Trudeau said.

"On behalf of the Government of Canada, we affirm our loyalty to Canada's new king, His Majesty King Charles III, and offer him our full support."

Trudeau and numerous world leaders are expected to be at Queen Elizabeth's funeral on Monday, September 19.

This article's cover image was used for illustrative purposes only.