A New Zealand man who sexually abused a 5-year-old boy in Cairns is being extradited back to New Zealand.

Queensland's Courier Mail reports 43-year-old Craig Edward Broadley from Lower Hutt pleaded guilty to nine charges of indecent treatment, and is expected to be sent back across the Tasman within days.

Broadley travelled to Australia in 2010 and 2011 after the boy's adoptive parents offered him up for abuse.

Former Cairns man Peter Truong and his American partner Mark Newton are serving sentences in the US for farming out the boy, whom they bought from a Russian surrogate mother, to a paedophile network.

Police claim a search of Truong and Newton's devices later uncovered chat logs, images and video which allegedly identified Broadley as having "engaged in the sexual abuse and taken hundreds of indecent images".

Broadley was arrested in New Zealand in August last year.