The Department of Fine Arts has filed a complaint with police seeking to halt the ongoing demolition of the Supreme Court buildings.
Before-and-after images show how the new Supreme Court complex would tower over its neighbours. Conservationists argue that it will lessen the aesthetic value of the Grand Palace next door.
Department director-general Sahawat Naenna filed the complaint with the Chanasongkram police station on Saturday.
He said the historic building, built in 1939 by the Pibulsonggram government to celebrate the return of Thailand's judicial sovereignty, should be kept because it is a national heritage site.
The Supreme Court has decided to continue with the demolition of its old building, which is expected to take three to four months.
The court insists it has the right to continue with its plan to replace the ageing structure with a new, much bigger office, citing a cabinet resolution passed in 1988.
The new structure would dwarf many of the other public buildings in the historic Rattanakosin area. The old courthouse was registered as a historical building in 2009.
Traditionalists have frequently expressed their dislike for the public buildings erected by the Pibulsonggram government. Like the Supreme Court offices, many feature the "modern international" architectural style popular in that era. The style has come to be closely associated with fascist regimes in the 1930s in Europe.
The new court building has been designed in the style of modern Thai architecture.
Court officials in charge of the project noted that the Fine Arts Department did not object to the 1988 cabinet ruling authorising the building of a new headquarters.
The department conceded the fact, but noted that the cabinet decision took place before the building was declared a historic site.
Chatri Prakitnonthakan, an architecture lecturer at Silpakorn University, has noted that the new building would breaches the building control code, which sets a 16-metre height limit for any new buildings in inner Rattanakosin.
He has also cited a study on the courthouse's safety by architecture lecturers from Chulalongkorn University. The study, commissioned by the court itself, said renovation would more cost-effective than building a new structure, which would cost more than 2 billion baht.