A Big Brother contestant is under investigation by police after making jokes about child pornography during a live feed of the reality show.

Spencer Clawson, a season 15 wannabe, was overheard making references to child porn while talking to fellow houseguests Amanda Zuckerman and Andy Herren.

The comments were made while he was pretending to be a fellow contestant, McRae Olson.

Clawson from Conway, Arkansas, said: "I like to beat off to child porn. Did I ever tell y'all about that? I love it.

"Beating off to child porn is my favourite thing. I love it when they're around 3 or 4 years old.

"My favorite ones are when you can tell they're in a basement."

Zuckerman and Herren quickly changed the subject but moments later the police were alerted to the railroad conductor's comments.

"Due to the nature of the comments, our department moved quickly to look into the matter," police chief AJ Gary in Conway, Arkansas, told TMZ.

"At this time we haven't found that any criminal act was committed."

Big Brother broadcaster CBS condemned Clawson's comments as offensive and did not represent the network.

A spokesperson said: "At times, the houseguests reveal prejudices and other beliefs that we do not condone."

Clawson came under fire in July when he described Hitler as a gifted speaker.