Two European men who posed with fake breasts and a pregnant stomach prosthesis are believed to have been used in the Katter Australian Party's anti-gay marriage advertisements without their consent.

The image of two shirtless men embracing with something pixellated between them was used as the centrepiece of a highly controversial political advertisement targeting Greens leader Bob Brown and Queensland Liberal National Party leader Campbell Newman.

A photo used in an anti-gay marriage ad by Katter's Australian Party. It has been traced to a stock photo website called 123RF, and credited to a French photographer called "Ostill".

Katter’s Australian Party Queensland leader Aidan McLindon today claimed the image had previously been used by the local gay community in an advertising campaign, an assertion rejected by the organisation that ran last year’s controversial Rip’N’Roll safe-sex ads in Brisbane bus shelters.

“In fact the image that is on television the gay community have been quite openly using on all their ads in school bus stops,” Mr McLindon told ABC News 24.