The Fine Arts Department says half of 20,000-30,000 art objects seized from the homes of disgraced former Central Investigation Bureau chief Pongpat Chayapan could be fake.
Department chief Borvornvate Rungrujee was speaking to the media a day after fine art experts began examining the seized items to authenticate them.
Police chief Somyot Pumpunmuang showed off the impressive hall of antiquities to the media on Nov 25, but it turns out that half of them have been certified as fakes.
"At a glance, about half of all seized objects might be fake," he said.
Mr Borvornvate said, however, 13 Khmer-style carved sandstone antiques found in Pol Lt Gen Pongpat's possession do not belong to Thailand, but are believed to have originated in Cambodia, Myanmar and Laos.
He said the antiques were among 80 large-sized objects authenticated so far by fine art experts.
He said the value of the authenticated items stood at more than 50 million baht.
"The 13 Khmer-style carved sandstone objects are mainly works of art from the early Buddhist era.
"They should have been kept at religious places or Khmer temples, and should not be owned by an individual.
"These antiquities might have been brought into the country from Cambodia, Myanmar or Laos," Mr Borvornvate said.