A grand jury in the United States has indicted a Melbourne man on charges of attempted child sex trafficking after he allegedly travelled to the US with the intent to meet with children.

The jury handed down its decision in the US District Court in Los Angeles on Friday, but the indictment was only made public yesterday afternoon (AEST).

Michael John Quinn was arrested in Los Angeles last weekend after allegedly paying an undercover agent $250 in an attempt to procure sex with a six-year-old boy.

The 33-year-old was on a rugby trip in the US when he was caught during the undercover sting on May 21.

The jury handed down its decision in the US District Court House in Los Angeles. ( AAP: Peter Mitchell )

Quinn was charged with travelling to the US for the purpose of illicit sexual conduct with a minor and attempted sex trafficking of a child, which carries a maximum sentence of life in prison.

Prosecutors said Quinn was under the impression a pimp would deliver him the young boy.

According to a criminal complaint filed in Los Angeles, Quinn contacted a social networking website that caters to individuals with a sexual interest in children, unaware that he was talking to undercover federal agents.