Indonesia is seeking the return of hundreds more smuggled orangutans from Thailand after authorities there agreed to send back more than 50 of the apes while they wait for DNA tests to prove their origin.

In 2003, Thai officials seized 114 orangutans from a Bangkok zoo, where they were forced to perform mock kickboxing matches in a show which became one of the zoo's main attractions.

Last week, Thailand agreed to send 53 of the saffron-haired animals to Indonesia while DNA tests are conducted to determine whether they originated from Indonesia or Malaysia.

But the spokesman for Indonesia's forestry ministry, Masy'ud, said officials were negotiating for the return of more orangutans from Thailand.

"We believe hundreds of orangutans have been smuggled to Thailand. We are trying to negotiate for their return," Masy'ud told AFP.

He said he believed only very few of the orangutans smuggled to Thailand were from the Malaysian part of Borneo island.

Conservationists hailed last weekend's decision as a small victory in the struggle against the illegal wildlife trade.

Orangutans are the only great ape to be found outside of Africa, and are native to the island of Sumatra in Indonesia and to Borneo.

Experts say only about 27,000 remain in the wild and that populations are fast declining due to deforestation and trafficking. They are an endangered species and their trade is banned internationally.

At least 700 orangutans are believed to be smuggled annually in Southeast Asia, with an estimated 100-300 trafficked through Thailand alone.