Two women have been arrested on suspicion of trafficking a child at an orphanage in a Hanoi pagoda renowned for rescuing abandoned babies, Vietnamese media reported on Monday.

Nguyen Thi Thanh Trang, the 36-year-old manager of the orphanage in the capital's Bo De Pagoda, was arrested on Sunday pending a police investigation into the alleged trafficking of a 1-year-old boy for $1,700, Tuoi Tre newspaper said.

Another woman, Pham Thi Nguyet, 35, was also arrested, while three others have been questioned over the same allegation, the report added without clarifying their roles at the pagoda.

The Bo De Pagoda in Hanoi is famous for its orphanage, where dozens of abandoned children are cared for, including the disabled, teenagers with Down syndrome and blind babies.

The boy, who was believed to have been left at the pagoda's entrance at birth, disappeared suddenly "without reason", the report said. Complaints led to the police investigation, the report said.

Officers discovered that the boy was "in fact trafficked" in exchange for $1,700.

The probe is ongoing to identify whether there were any other similar cases involving the orphans.

As of mid-July, the pagoda was home to 145 orphaned, abandoned or disabled children as well as elderly people in need of care, Tuoi Tre said.