Katy Perry has criticised Australian opposition leader Tony Abbott over his negative stance on gay marriage.

The politician phoned in on Sydney's 2DayFM radio station recently when the 'Roar' star was appearing on the show.

He said he called because his three daughters are big Perry fans - but the singer was more keen to discuss Abbott's opposition to gay marriage.

Abbott asked Perry when she is coming back to Australia, to which the star replied:

"Oh come on, that's not a political question. Let's talk about gay marriage. I love you as a human being but I can't give you my vote. I just don't believe in your policies so that's what a lot of people should be doing."

Abbott, who has an openly gay sister, is running against Prime Minister Kevin Rudd for election and they differ on their same-sex marriage stance.

Speaking after the phone call about Perry, the Aussie politician said: "I respectfully disagree with a number of people, including my own sister, on this subject, but no doubt we'll all continue to say our piece."

Abbott, however, concluded: "My daughters for once were envious of their dad."