Indonesian police have arrested a suspected wildlife smuggler after discovering nearly two dozen rare birds jammed inside plastic water bottles in his luggage.

The 37-year-old man was stopped by police on Monday as he alighted from a passenger ship in Surabaya, a city on the main island of Java.

Photographs show the birds, mostly yellow-crested cockatoos, peering out of the bottles after being found by officers. The bottoms of the bottles had been cut off to squeeze the birds inside.

The head of the criminal investigation unit at the Tanjung Perak port, Aldy Sulaiman, said police found the live birds stashed inside the man's luggage.

"We found 21 yellow-crested cockatoos and one green parrot," he said.

"All the birds were found inside water bottles, which were packed in a crate."

A police officer holds a water bottle with a yellow-crested cockatoo put inside for illegal trade. ( Reuters: Antara Foto/Risyal Hidayat )

The birds have since been sent to Indonesia's natural resources conservation office, which deals with wildlife-trafficking cases.

Mr Sulaiman said the man — whose identity was not disclosed in line with normal criminal procedure in Indonesia — had admitted to carrying two birds for a friend but claimed to know nothing about the other animals.

If found guilty of smuggling, the man, from near Surabaya, could face up to five years in prison.

Yellow-crested cockatoos are native to Indonesia and neighbouring East Timor and considered critically endangered, according to the International Union for Conservation of Nature.

They are different to the larger and more common sulphur-crested cockatoo which is mostly found in Australia and New Guinea.

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AFP