A former criminal investigator has warned the only way a Chinese man accused of throwing hot coffee on a baby in Queensland will ever be arrested is if he willingly returns to Australia.

Nine-month-old Luka had boiling hot coffee poured over him in Brisbane's Hanlon Park on August 27 last year.

The man allegedly responsible poured an entire thermos on Luka before fleeing the country from Sydney to China, evading capture.

Ever since, Australian authorities have been urging China to return the unnamed 33-year-old for prosecution, but the requests have constantly been denied.

Chinese law dictates that no Chinese nationals can be extradited to face prosecution abroad for crimes allegedly committed overseas.