“You sort of know when Australia Day is coming up,don't you,when you get the annual conservative outing to put politics into Australia Day?

“It's what the conservatives do to keep their base happy,talk about this.”

He was non-committal on the question of whether to take citizenship ceremonies away from councils that refused to hold them on Australia Day,as a handful have done,citing concerns about the sensitivity of January 26 to Indigenous Australians.

“There are 537 councils in Australia,about 530 of them already have citizenship ceremonies on Australia Day. We'll see what they're proposing,” Mr Shorten said.

On the question of a dress code,Mr Morrison said the vast majority of people attending ceremonies dressed respectfully.

“But sometimes,people turn up in dress that’s just not appropriate and doesn't show the appropriate respect,both for our national day and for citizenship itself.

"I'm a prime minister who is for standards and I'm putting standards on councils,if they want to run citizenship ceremonies.”

A spokeswoman for the Minister for Immigration and Citizenship,David Coleman,said the clothing of attendees “should reflect the significance of the occasion” and said people could wear national or cultural dress,but she did not answer questions on what rules would apply nor who would decide what dress was appropriate.