After an investigation, which went on during a decade, the NGA said it had concluded that the three bronze sculptures were, on the balance of probabilities, exported from their country of origin illegally.
"The decision to repatriate these sculptures to the Kingdom of Cambodia is the culmination of years of research and due diligence that would not have been possible without the support of the Cambodian Government through the Ministry of Culture and Fine Arts," NGA director Nick Mitzevich said in an official statement.
"We are grateful for their support in identifying the place of origin of these culturally significant sculptures and are pleased we can now return them to their rightful home," Mitzevich said.
The sculptures will remain on display at the gallery for three years on loan while the Cambodian Government prepares a new home for them.
“The return is a miracle and sets an example for the world."
The @NatGalleryAus has agreed to return one of the centre pieces of its Asian collection to Cambodia, after an investigation revealed a trio of 9th-century sculptures were likely stolen.
Susan Templeman, the Australian Government's Special Envoy for the Arts, said the repatriation was an example of the shared respect between the nations. "It is an opportunity to put right a historical wrong but also to strengthen our ties and deepen our understanding," she said.
The three 9th-10th century bronze sculptures were purchased in 2011 for 2.3 million Australian dollars (1.5 million U.S. dollars).
They were removed from display in the gallery's collection in 2021 amid an investigation into their provenance.