Amid pomp and pageantry not seen for more than half a century, King Charles and Queen Camilla arrived at Canada's Parliament today.

Their Majesties were escorted in a horse-drawn landau and met by a Royal Salute from a 100-strong Guard of Honour at the Ottawa Senate building.

The event is the highlight of the couple's whirlwind visit to the North American nation, Charles' first as king.

He was invited by the country's Prime Minister Mark Carney to formally open the new session of parliament in what is widely being interpreted as sign from Canada that its sovereignty is not for sale.

As a constitutional monarch, King Charles cannot publicly comment on recent threats by US President Donald Trump to 'annexe' Canada and make it American's '51st state'.