Thai police have found at least 35 orang-utans alive and caged during a raid on a controversial Bangkok zoo.
The zoo has angered campaigners with its orang-utan boxing show
Police suspected the orang-utans had been hidden after an earlier raid found only 69 of Safari World 's 110 apes.
The whereabouts of about six of the apes - a highly endangered species - are still a mystery.
On Thursday, the zoo's owner was charged with illegally importing the animals, which have been used to stage controversial kick-boxing fights.
Most of the missing animals were found in the zoo after police conducted a head-count on Friday, Forestry Police Colonel Vijit Nantawong said.
A zoo official, Vincent Chu, said the animals had been moved to protect them from illness, and denied they had been deliberately concealed.
Orang-utan are a highly endangered species found only in the jungles of Indonesia and parts of Malaysia.
Police raided the zoo last week seeking to confiscate the animals in response to complaints by Indonesian environmentalists.
But a lack of suitable cages to re-house the orang-utans meant they had to stay on at the zoo.
The zoo's owner, Pin Kiewkacha, denies that the zoo's orang-utan population was smuggled into the country, and says the animals were either obtained legally or were the products of successful breeding programme.
Hair samples of the apes have been taken in the hope of establishing their origins.
Last week, the Thai authorities forced Safari World to suspend its orang-utan fights while they investigated claims of cruelty and exploitation.
The orang-utans, in boxing gloves and brightly-coloured shorts, have featured at the park for decades.