A man wanted on a warrant for manslaughter over the death of a six-year-old boy at a self-healing conference in Sydney has been arrested at London airport.

Police are now working to complete an application for Hongchi Xiao, 53, to be extradited back to Australia.

Between April 22–28, 2015, a man and a woman took their six-year-old son to a self-healing conference which Xiao was involved with at a facility on Park Road, Hurstville.

Xiao is a prominent 'slapping therapist' and promotes the controversial practice of Paida Lajin which aims to release the toxins from patients by slapping one's skin.

The boy was a type-1 diabetic and Paida Lajin claims to eradicate the symptoms of diabetes.

Just before 10:00pm on April 28, emergency services were called to a nearby hotel on Forest Road, Hurstville, following reports the boy had been found in an unconscious state.

Paramedics attended the location and commenced CPR, however the boy could not be revived.

Xiao has appeared before Westminster Court where he was remanded in custody until June 8.

In March this year, the mother, 41, and father, 56, of the boy who died were charged with manslaughter.

They were arrested at their home in Prospect and were granted conditional bail.

They are due to appear again in court this month.