The Australian MP, his gay brother, and a family feud over a 'homophobic rant'

Outspoken, Stetson-wearing firebrand finds himself on receiving end of the tough talk

Bob Katter has incensed his half-brother Carl, right, with an advert attacking gay marriage (Getty Images)

Bob Katter, a maverick Australian MP with a sprawling Queensland electorate and a penchant for Stetsons, is known for his colourful views on social issues. But when he made a television commercial attacking same-sex marriage, he offended not only gay and lesbian groups, but his own half-brother, Carl.

Now Carl, who is gay, has hit back with a TV advertisement of his own, in which he decries "my half-brother's homophobic ad". He has also been interviewed widely, pouring scorn on Bob's "hatred and bigotry".

Their battle was triggered by the state election campaign in Queensland, where voters go to the polls in 10 days. Although Bob Katter is an independent in the federal parliament, he recently founded the Australian Party, dedicated to protecting the rights of compatriots who "like shootin', huntin' and fishin'". But its commercial about gay marriage – which features two shirtless men embracing, their pose pixelated seemingly to imply it is too offensive to be shown unedited – has outraged mainstream politicians and even some of its own candidates.

The ad was designed to undermine the main opposition Liberal National Party, led by Campbell Newman. It highlights Mr Newman's support for gay marriage by superimposing a picture of his head nodding to continually replayed footage of another politician, Greens leader Bob Brown, saying he backs the legalisation of gay marriage. In another shot, Mr Newman is seen folding a skirt in a factory. The ad asks: "Do you think he'll really stand up for your family values?" It also suggests he will not oppose "minority groups". This is despite Mr Newman accepting his party line of opposing new state legislation allowing same-sex civil unions.

Carl Katter says that when he saw Bob's ad, "my thoughts went to the young Australians who will see this on television, telling them they don't belong, that they're somehow inferior".

He adds: "Our leaders shouldn't be telling [us] it's OK to discriminate. We shouldn't have to put up with politicians who seek election by appealing to the worst in human nature."

Popular in his constituency, which he has held for 20 years, the white-haired Bob Katter calls himself "a wild boy from wild country". An outspoken advocate for rural Australia and a die-hard climate-change sceptic, he dislikes supermarkets, asylum-seekers and government red tape.

Carl and Bob Katter have not spoken for years. Carl dismissed Bob's recent declaration that he admired Carl's "candour, his forthrightness". He told Sky News: "I don't think he respects my [efforts] to create a fairer and [more] equal Australia."

Speaking on ABC radio, Carl said that if the Australian Party's ad was "targeting a cultural minority, targeting women, targeting indigenous Australians, it would not be allowed on air". Carl said: "He doesn't see any harm in [it], and that's really disturbing. And it seems he's got some obsession with homosexuality. It's really bizarre."