The Fine Arts Department has ordered the suspension of construction of the Den Chai-Chiang Khong railway in tambon Toong Kwao of Phrae's Muang district after the discovery of ancient artefacts aged between 400 and 500 years in the construction site.
The antiquities included Buddha amulets, broken earthenware and a bronze gong.
Chinnawut Winyalai, the director of the 7th Regional Office of Fine Arts in Chiang Mai, said that the objects were initially estimated to be between 400 and 500 years old.
Many more artefacts are expected to be found, he added.
Fine Arts Department archaeologist Phonphayuha Chaiyaros said that the ancient gong will be examined to ascertain its true age. The department says it will later publish the findings.
Somrit Sukmee, the village headman of Moo 3 village, said the area was home to an abandoned temple called Wat Pa Soong.
Thus, in order to preserve the ancient treasures potentially hidden at the location, the National Office of Buddhism (NOB), which legally owns the temple, should have acted to inform the SRT about the existence of the temple and asked the Fine Arts Department to inspect the area first before the railway route was planned and the construction project was launched, Mr Somsit added.
Any agency found to have neglected their duty should face legal action, he said.
"Authorities need to discuss how to proceed further. We have to listen to the voices of villagers regarding how they would like to preserve the place," he said.
"At this time, the department still doesn't know where the train line ends. It is something we will have to continue studying in the next two months," Mr Chinnawut said.
Construction has now been suspended by the order of the Fine Arts Department to allow for a thorough search through the site.