The King and Queen Camilla are set to arrive in Australia for the start of an historic tour of the South Pacific.

The six-day trip to Canberra and Sydney will be Charles’ first to a realm – countries where he is head of state – since he became monarch following the death of Queen Elizabeth II.

The King and Queen will later travel to Samoa for a three-day state visit and meet world leaders taking part in a Commonwealth Heads of Government Meeting which Charles will formally open.

Dr George Gross, royal historian and visiting research fellow at King’s College London, said: “This is a tour of significant firsts. Although King Charles III has travelled to Australia many times, this will be his first visit there as sovereign and the first tour to the country by a reigning monarch since 2011.

“It will also be the King’s first official overseas tour since his cancer diagnosis, his first to a Commonwealth realm and, while visiting Samoa, he will lead the first Commonwealth Heads of Government Meeting of his reign.

“It is notable too that he is visiting Australia in the year after his coronation, as this echoes the 1954 tour by his late mother, Queen Elizabeth II following her coronation in 1953.”

Small symbolic protests are planned by the anti-monarchy group Republic, with its chief executive officer Graham Smith travelling to Australia to lead the events in Canberra and Sydney.

The Australian Republican Movement has branded the visit “The Farewell Oz Tour” and reports claim Australia’s six state premiers will miss a reception for the King and Queen in Canberra on Monday.

Charles’s health is a factor, as the King was diagnosed with an undisclosed form of cancer earlier this year and will be pausing his treatment while he is away from the UK.

The overseas tour has been curtailed on advice from doctors, with a visit to New Zealand dropped from the itinerary and other changes made to the programme.

Charles and Camilla will be greeted when their plane lands at Sydney by a number of dignitaries including Australia’s governor-general Sam Mostyn, the King’s representative, and prime minister Anthony Albanese and his partner Jodie Haydon.

The King and Queen will later sit down with Mr Albanese and Ms Haydon for private talks, and with Saturday designated a rest day the tour will begin in earnest on Sunday.

During the visit Charles will meet colleagues Professor Georgina Long and Professor Richard Scolyer, named as Australians of the year 2024 in recognition of their pivotal work on melanoma, one of Australia’s most common cancers.

Other highlights of the Australian visit will see the royal couple spending time in the capital Canberra meeting leading figures and paying their respects to the country’s fallen, while in western Sydney they will attend a community barbecue – a staple of Australian culture.