Is it Australia Day - or April Fool's Day?

That was a question being posed on social media after an early morning statement from Prime Minister Tony Abbott revealed the Queen's husband, Prince Philip, had been awarded a knight of the Order of Australia, the country's highest honour.

The 93-year-old Duke of Edinburgh, who has made a string of controversial and memorable gaffes during his wife's reign, became a trending topic on Twitter in Australia shortly after Mr Abbott announced that he would receive the honour alongside Air Chief Marshal Angus Houston.

The online reaction was largely one of incredulity, and it was far from complimentary.

In particular, critics referred to Prince Philip's 2002 visit to Australia with the Queen, when he asked an Aboriginal man: "Do you still throw spears at each other?"

Mr Abbott dismissed the criticism, describing the negative reaction on social media as "electronic graffiti".

Mr Abbott was peppered with questions at an Australia Day function in Canberra about whether there were Australians who would have been more deserving of the award than a British royal.

"I'll leave social media to its own devices. Social media is kind of like electronic graffiti and I think that in the media, you make a big mistake to pay too much attention to social media," Mr Abbott said.

"You wouldn't report what's sprayed up on the walls of buildings."

I want to be angry about Prince Philip being made a Knight of Australia, but I'm too busy laughing to be honest! :) pic.twitter.com/9lesqwOUWt — John Anthony James (@JohnJamesOZ) January 25, 2015

So TA gave Prince Philip a knighthood, kind of like someone giving Richard Branson's wife their frequent flyer miles #philgate — Deb R (@BrissieDeb) January 25, 2015

Surely Shane Warne was more deserving of a knighthood than Prince Phillip? Sir Shane? @ShaneWarne — Stephen Koukoulas (@TheKouk) January 25, 2015

Once the Queen reminds him where Australia is, I'm certain Prince Philip will be delighted with his new knighthood. http://t.co/zx8F6Ef1gS — Richard Hull (@richardhhull) January 25, 2015

I'm starting to wonder if Tony Abbott is actually just one of the Chaser boys waiting for us to realise. http://t.co/pTWp0smBoU — Hugh Rundle (@HughRundle) January 25, 2015

Is there no one in the office capable of uttering the simple phrase: "This is a dumb idea that is all pain and no gain?" — Chris Kenny (@chriskkenny) January 25, 2015

Prince Philip is like "Frankly I am not amused by all this fuss. I've never been fond of Austria." — Paul Webster (@p_webs) January 25, 2015

Trying to Australianise the monarchy. Reminds me of that episode of A Country Practice where Bob(?) thought he was an earl. — Terri Butler MP (@terrimbutler) January 25, 2015

Congratulations Prince Philip on your knighthood, and congratulations the Middle Ages on becoming a thing again! — Jesse Thompson (@jethom17) January 25, 2015

So proud. Australia knights Prince Philip. Who needs satire? — Kevin Airs (@KevinAirs442) January 25, 2015

Prince Philip? Memo Abbott, it's #Straya day today, not April Fools day. — Scott Ellis (@blahblahellis) January 25, 2015

What next? Will Abbott make his horse a Senator? #auspol — Dave Noonan (@DaveNoonanCFMEU) January 25, 2015

Coming up in the next exciting episode of My Australia Day Honours List Rules... pic.twitter.com/QOct9GzJp4 — James Jeffrey (@James_Jeffrey) January 25, 2015

Australia Day gets even more of an 18th Century feel with the appointment of new knights http://t.co/0DnYB1lRwC — Nick Bryant (@NickBryantNY) January 25, 2015

Prince Philip: "Oh look, Lizzie. The colonies are giving me a knighthood! It's like they think they're people." [sips tea & shrugs, baffled] — Benjamin Law (@mrbenjaminlaw) January 25, 2015

People focussing on Prince Philip's casual racism. Let's not forget: "To female sea cadet last year: "Do you work in a strip club?" Arise! — Tony Wilson (@byTonyWilson) January 25, 2015

Giving a Knighthood to Prince Philip is like giving a Beyoncé CD to Jay-Z. Surely he could just pick one up at home. — Adam Hills (@adamhillscomedy) January 25, 2015

EXCLUSIVE PIC: First reactions from Buckingham Palace to exciting news about Prince Philip's Australian knighthood... pic.twitter.com/rwHiIYiRDl — Rohan Connolly (@rohan_connolly) January 25, 2015

- with Lisa Cox