Australian rugby player and IVF geneticist Michael Quinn has told a US judge he is not guilty of attempting to pay $US250 to have sex with a six-year-old boy in a Los Angeles hotel room.

Quinn, who appeared in the US District Court in downtown Los Angeles on Tuesday, will stand trial on August 16 and if found guilty faces a maximum sentence of life in jail without the possibility of parole.

The 33-year-old entered not guilty pleas to one count of attempted child sex trafficking and one count of travelling with the intent to engage in illicit sexual conduct.

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Quinn allegedly told an undercover US Homeland Security investigator he was interested in having sex with boys, authorities allege.

When he arrived in the US last month investigators tricked Quinn into believing a pimp would deliver a six-year-old boy to a beachside hotel room, authorities alleged.

Quinn allegedly handed over $US260 – $US10 more than was agreed upon – and was arrested soon after.

The Monash University-educated geneticist, who worked at a leading Melbourne IVF clinic, has been in custody since his May 21 arrest.

Quinn, a member of the Melbourne Chargers rugby club, was in the US to play in the Bingham Cup in Nashville, Tennessee, a tournament honouring September 11 hero and pioneer of gay rugby clubs, Mark Bingham.

-AAP