Authorities on Koh Samui are widening an investigation into construction permit forgery involving at least 10 projects and potentially involving both municipal staff and outsiders.

The probe follows the discovery of forged signatures on a building construction permit (known as an Or.1) issued by the public works division of Koh Samui Municipality, raising concerns over rules and the safety of several high-end villa projects, according to Matichon Online.

A municipal legal officer said the first cases were found in October last year, involving one private construction project and one commercial building modification.

In both cases, permit holders presented official-looking documents to inspectors. However, checks revealed the permits were not registered in the municipal system, and signatures, including that of the mayor, were forged.

A clerical officer who was linked to the documents has been removed from duty pending an investigation.

Municipal authorities are now expanding the probe to determine whether senior officials in the engineering division were involved or benefited from the scheme.

Officials said it was unlikely that a junior officer could have carried out such actions alone, raising suspicions of a wider network.

Attention is also focusing on possible links to external intermediaries acting as “brokers” to connect developers, particularly villa operators seeking fast-track approvals, with insiders able to produce fake permits.

The suspect at the centre of the case reportedly joined the civil service in June 2022.