Australia's prime minister on Monday dismissed criticism of his decision to make the husband of Queen Elizabeth II an Australian knight, saying Prince Philip has a long history of service Down Under.

Prime Minister Tony Abbott's announcement that the Duke of Edinburgh would be awarded Australia's highest honor came on Australia's national holiday, prompting some to question the wisdom of knighting a British royal on a day meant to commemorate Australians.

"It's a time warp where we're giving knighthoods to English royalty," Opposition Leader Bill Shorten told Fairfax Radio. "On Australia Day, we're talking about Australia, Australian identity. The government's managed to find a British royal to give a medal to, a knighthood to."

Adam Giles, government head of the nation's Northern Territory, questioned whether he'd confused his holidays.

"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."

And Terri Butler, lawmaker with the opposition Labor party, tweeted her own puzzlement: "He didn't really knight a prince, did he?"

Despite the criticism, Abbott insisted the prince was a good friend of Australia and therefore, a good candidate for the nation's knighthood.

"The monarchy has been an important part of Australia's life since 1788," Abbott said. "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 organizations."

The Order of Australia — the nation's official honor system — first introduced categories for knights and dames in 1976, and awarded 14 people those honors until the categories were abolished a decade later. Abbott reinstated the knights and dames division to the Order in 2014 after gaining approval from the Queen.

Former Defense Force chief Angus Houston, who has overseen the search for missing Malaysia Airlines Flight 370 off Australia's west coast, was also named a knight on Monday.