An Australian MP's gone off the rails as the country takes a step closer to marriage equality.

The House of Representatives is expected to vote on the legislation either today or tomorrow, after expanding debate time to allow all MPs to speak.

Independent Queensland MP Bob Katter shocked the House with his speech, bringing up conspiracy theories, inferring gay people were murderers, and that boys are being made to wear dresses.

Australia correspondent Donna Demaio told Rachel Smalley it was a rambling, nonsensical speech that's been poorly received by the public.

"We've heard from the Sydney Mardi Gras director, Jessie Matheson, who summed it up best I think: 'Bob Katter made the most foul speech I've ever heard, it was just so bad'.

LISTEN ABOVE AS DONNA DEMAIO SPEAKS WITH RACHEL SMALLEY