The 10,000-page report in seven large cardboard boxes contains information from 63 witnesses. It implicates four senior Bangkok Metropolitan Administration (BMA) officials in specification-rigging.

The road projects are worth Bt20 billion.

Officials named in the report include deputy governor Samart Ratchapolsitte, Phattharut Thantharanont, deputy head of the BMA’s Public Works Department, and Uthai Khankaew, an engineer with the department.

Prasong Suriwatthanachai, an executive of Unique Construction and Engineering Co Ltd, which won some of the projects, was also named in the report. A source said the DSI would ask the Anti Money Laundering Office whether such specifications-rigging rendered the riggers liable to assets seizure.

Meanwhile the BMA issued two statements defending its role in the road projects and another scandal involving the purchase of fire trucks from Austria worth Bt6.68 billion.

BMA spokesman Buddhipongse Punakanta said 100,000 copies of the first statement had been sent to city residents and 30,000 of the second to BMA workers.

Both statements cited good governance as a core principle of the BMA’s work.

They vowed that all BMA officials were diligently working to serve city residents.