Charles meets Australia's republican PM Malcolm Turnbull

The Prince of Wales has met Australia's staunch republican Prime Minister Malcolm Turnbull who in the past has strongly criticised both Charles and the British monarchy.

The two men met on the tarmac at a military base in Canberra, a moment that had been billed as potentially awkward for the heir to the throne given Mr Turnbull's views.

But as the group sheltered from rain under umbrellas the greetings were warm with handshakes and smiles between the two men and their wives.

It is believed to be the first time Charles has met Mr Turnbull who is Australia's fourth leader since 2013 and was once the public face of the country's republican movement.

In his 1993 book The Reluctant Republican he passed personal criticism on both Charles' marriage to Diana, Princess of Wales, something he described as "a miserable pretence", and his relationship at the time with Camilla.

Mr Turnbull also highlighted his frustration at Charles giving the longest speech on Australia Day in 1988, the bicentennial year of the nation.

He said the address "was not uttered by an Australian. It was given by an Englishman, Prince Charles", adding: "Our own national leaders were just warm up acts for Prince Charles."

Mr Turnbull is well known as being the barrister who successfully defended former MI5 officer Peter Wright in the Spycatcher trial where the British government sought to block publication of his controversial book.

He was chairman of the Australian Republican Movement for seven years and described his own Liberal leader, John Howard, as "the prime minister who broke this nation's heart'' when a referendum to ditch the monarchy failed in 1999.

But in recent years, the popularity of the Duke and Duchess of Cambridge and their children has dampened enthusiasm for replacing the monarch with a president, with Prince George being dubbed the "republican slayer'' after proving a hit with the Australian public when he joined his parents on a tour of the country last year.

Mr Turnbull has indicated he has no immediate plans to ditch the monarchy saying: "My own view for what it is worth ... is that the next occasion for the republic referendum to come up is going to be after the end of the Queen's reign. While I am a republican there are much more immediate issues."

The prince and the prime minister are due to hold talks later but first attended a national Remembrance Day ceremony at the Australian War Memorial joining hundreds of guests commemorating the Commonwealth country's war dead.

As heavy rain fell on those gathered at the open air ceremony, hymns were sung and wreaths were laid by the prime minister, Charles, Governor General Sir Peter Cosgrove, leading Australian figures and representatives from other nations.

The Royal party then made their way to the memorial's roll of honour where the names of the fallen are embossed on long walls and a tradition has developed of family members placing a poppy next to the names of their loved ones.

Charles and Camilla were joined by Rear Admiral Ken Doolan and his wife Elaine as they walked past the names and stopped to leave a poppy.