Australian politician Bob Katter’s gay brother has criticised him for a new advert which attacks an opponent’s support for equal marriage rights for gays.

Mr Katter, federal MP for Kennedy, launched Katter’s Australia Party last year and released a new attack ad against an opponent using only his support for gay marriage against him.

The ad includes footage of Liberal National Party leader Campbell Newman saying he supports such a move and asks whether voting for him is “a vote for gay marriage”.

Last year, Katter, who had been an independent MP before forming his party, said the idea of equal rights for gay couples “deserves to be laughed at and ridiculed”.

The ad asks how well viewers “know Campbell Newman” and questions whether he can be relied upon to “stand up to the Greens and other minority groups” while displaying a picture of a shirtless male couple whose chests are pixellated.

It then repeated shows footage of Mr Newman saying “I support gay marriage”, followed by the caption “That’s right, he supports Gay Marriage!”

The MP’s gay half-brother Carl Katter told Australia’s ABC News: “Initially I actually thought it was fake, it was a joke, but you know I find them pretty offensive.

“I’m more concerned about the damage that they can facilitate in regional areas for predominantly gay and lesbian youth.

“But I mean it’s also a great indication that this fledgling party are trying desperately to steal the conservative vote, but I think it’s going to backfire.”

He added: “There’s a great level of desperation there to spend the money on an ad addressing marriage equality, which is now a federal issue. So you know, they’re just playing the politics of hate.”

It was revealed today that the pixellation was covering a prosthetic pregnancy bump and that the image had been taken from a separate campaign for safer sex which ran last year.

Katter’s Australian Party occupies one of the 150 seats in the federal House of Representatives and two of 89 seats in the Queensland parliament.