Tran Hiep, a 50-year-old Vietnamese Australian anti-human trafficking campaigner, not heard from since 18 September

The wife of an Australian activist missing in Cambodia has implored the federal government to find him and bring him home.

Tran Hiep, a 50-year-old Australian Vietnamese democracy campaigner, was due to return to Bangkok, Thailand, to reunite with his wife Chloe Dang after a short trip to Phnom Penh, Cambodia, to meet with human rights defenders.