Police spokesman Ajiravid Subarnbhesaj said Chainarong Wongsunthorn was subject to transfer unless the case was closed swiftly. He said police had taken over investigation of the fires from the Justice Ministry's Central Institute of Forensic Science following the hand-over of power from military leaders to a civilian PM.

Senior investigators were in the province yesterday to consolidate police efforts. A two-hour meeting produced no conclusions.

Military and police intelligence sources suggested a local kamnan could be behind the blazes. The suspect, a resident of neighbouring Phichit province, allegedly had ties with local politicians and some senior officers of Police Region 6 - which oversees both provinces.