Will Charles face a new conflict with his visit to Australia?

• The planned visit to Sydney will coincide with the Commonwealth summit

King Charles will face the biggest test of his reign next year when he flies to Australia, where calls for the country to break from the Commonwealth and become a republic are growing.

The Mail on Sunday can reveal royal aides are preparing for a visit to Sydney coinciding with his first attendance as head of the Commonwealth at its summit meeting in Samoa.

A senior Australian government minister said last night the visit would lead to a “renewed conversation” about the country having its own head of state.

Charles will attend the Commonwealth Heads of Government Meeting (CHOGM) next October and is expected to extend the tour to visit Australia. New Zealand and Fiji.

Matt Thistlethwaite, deputy minister of the republic – an anti-monarchist position created in the Australian Labor Party last year – told the Ministry of State: “The King will always be welcome in Australia and warmly received by the Australian people. But in today’s Australia his visit will spark a renewed conversation about having our own head of state who lives with us, represents us and is Australian.”

Charles has already been criticized for yet to make an official visit to any Commonwealth country despite having been on the throne for more than a year.

Isaac Jeffrey, leader of the Australian Republic Movement protest group, added: “By the time Charles visits us, he will have been king of Australia for more than two years. “He hasn’t been in a hurry to visit us and that’s fine, we don’t need him.

A recent poll found that 78 per cent of 1,500 Australians believe the Royal Family should foot the bill for a state visit. In 2011, it cost Australian taxpayers $2.6 million (£1.9 million today) to host the Queen and Prince Philip.

Royal advisers will closely monitor Saturday’s referendum, where Australians will vote on whether to allow an Indigenous voice in parliament. If successful, the Labor government, under Prime Minister Anthony Albanese, has said it will hold a vote to test the appetite for being a republic if elected for a second term in 2025.

A YouGov poll of 1,200 Australians last month found 32 per cent want a republic as soon as possible, up 12 percentage points from a similar poll last year.

For his part, Charles is understood to have been left “disturbed” by the delay in receiving an official invitation from the Australian Prime Minister.

It is understood that if Charles were to travel to the country – his 17th visit to Australia – anti-monarchists would use it as a launching pad for their attempt to overthrow him as king.

Sources say opponents will focus on official commitments to make their case for an Australian to be the country’s first president.

They add that there have been “conversations on both sides” and that “the King has made it clear that he is interested in meeting as many Australians as he can when the opportunity arises.”

In contrast, Shadow Defense Minister Andrew Hastie told the State Office: “The king will be very welcome on his first visit.” There is a renewed enthusiasm for the Crown in Australia and a sense that we share something special and historic.’

But Prime Minister Albanese is in no rush to send a formal invitation. A source said: ‘It’s fair to say there has been some concern about it. As is protocol, the king cannot act on anything until he receives an official invitation.

The Palace did not want to discuss the details of the talks between the King and Albanese for a state visit.

In May, this newspaper revealed Charles’ plans to visit his first Commonwealth country, Kenya, at the end of the month. The Palace is expected to confirm this in the coming days.