Four endangered orangutans have been repatriated to Indonesia for conservation efforts.

The young apes, three Sumatran orangutans and one Tapanuli orangutan, were handed over to Indonesian officials in a turnover ceremony at the Suvarnabhumi International Airport, on December 23.

Sadudee Phanphakdee, director of the Cites Wildlife and Plant Protection Division, led the transfer as Thailand and Indonesia marked the 75th anniversary of diplomatic relations.

Wildlife authorities had rescued the primates from the illegal wildlife trade in separate operations in Chumphon and Bangkok this year.

Both species of orangutan were protected under local laws and the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).

Vets had cleared the orangutans for air travel, and placed them in two crates to prevent separation anxiety.

The animals left Thailand on Garuda Indonesia flight GA867 bound for Soekarno-Hatta International Airport in Jakarta.

Thailand said it has returned 78 orangutans to Indonesia across seven operations since 2006.

They said the repatriations supported efforts to combat international wildlife smuggling networks, and reflected the strong relationship between the two countries.

Thailand is a major transit hub for animal trafficking. With its porous borders with Myanmar and Cambodia, the country is a key route for smuggled wildlife across Southeast Asia.