The Australian prime minister has defended his decision to honour the Duke of Edinburgh with a knighthood, despite a social media backlash in which many said they thought the news was a joke.
Tony Abbott faced a barrage of questions on Australia Day, and has been accused of creating a "time warp" by awarding a member of Britain's royal family the country's highest honour.
The 93-year-old Duke has been granted the Knight of the Order of Australia award for a long life of duty and service, Mr Abbott said.
But some of the country's senior politicians, along with many Twitter users, aired their opposition to the announcement.
The government head of the Northern Territory, Adam Giles, said he did not think the news was serious on first reading.
"I woke up this morning and read the wires and I thought it was April Fool's Day," he said.
"I think it takes away from the legitimacy of the knighthood role. I think it makes a bit of a joke in a range of areas."
Opposition leader Bill Shorten said some thought the announcement was a hoax.
"I think that on Australia Day, where we're talking about Australia, Australian identity, the government's managed to find a British royal to give a medal to, a knighthood to. I've just been at citizenship functions, local breakfasts - some people there wondered whether it was an Australia Day hoax," he told Fairfax Radio in Melbourne.
Online reaction ranged from disbelief to mockery.
One Twitter user wrote: "So proud. Australia knights Prince Philip. Who needs satire?" while another said: "Congratulations Prince Philip on your knighthood, and congratulations the Middle Ages on becoming a thing again!"
Mr Abbott dismissed much of the social media reaction as having little "authority and credibility".
He told broadcasters: "I'll leave social media to its own devices. Social media is like electronic graffiti and I think that in the media you make a big mistake to pay too much attention to social media.
"In a sense it has about as much authority and credibility as graffiti that happens to be by means of IT."
He later added: "The monarchy has been an important part of Australia's life since 1788. And Prince Philip has been a great servant of Australia.
"He's been a great servant of all the countries of the Commonwealth. Here in this country, he's the patron of hundreds of organisations."
The Duke's knighthood was announced alongside that of Air Chief Marshal Angus Houston, for his military service and his involvement in the country's response to the MH370 and MH17 air disasters last year.
Mr Abbott cited Prince Philip's Duke of Edinburgh award scheme as having helped thousands of young people in Australia for more than 50 years.
The Duke's son the Prince of Wales was made a Knight of the Order of Australia in 1981.
The Duke last visited Australia in 2011, the year he turned 90.
He completed an 11-day official royal tour alongside the Queen, during which they visited Perth, Melbourne, Canberra and Brisbane.