The National Council for Peace and Order (NCPO) Thursday handed over to the Crime Suppression Division (CSD) five people allegedly linked to a Powergel explosives find in Pathum Thani last month.
Their arrest followed the discovery of 1,800 bars of Powergel in cardboard boxes on the back of a pickup truck in Thanyaburi, after police stopped it for a search on April 26.
The water-resistant, bar-like product is normally used in the mining industry for quarry blasting, tunneling and excavation. Powergel usually becomes volatile when mixed with a precursor, such as fuel oil.
According to NCPO judge advocate Burin Thongprapai, among the suspects was 46-year-old Pol Lt Yutthana Chidchol, a police officer from Sakhu station in Phuket's Thalang district and 55-year-old Boonlert Nanphimai, a wanted suspect in Pathum Thani's Thanyaburi district.
Ammonium nitrate fertiliser and more Powergel were later found during a search of Pol Lt Yutthana's house in Thalang, according to police reports.
Investigations into whether the explosives could be linked with the insurgency in the deep South are currently being carried out, the reports added.
Other suspects handed over Thursday included Nattachai Thanapatsatchaporn, 57, Channetti Thanapatsatchaporn, 55 and 47-year-old Sophon Termpanthunont.
Chayapol Chatchaidet, deputy commissioner of the Special Branch Police, said two other suspects were arrested at the time of the initial discovery in the pickup truck last month.
They were identified as Chayapong Kaew-in, 37 and Premwadee Boonchalee, 33.
According to Pol Maj Gen Chayapol, Mr Chayapong had said a 43-year-old engineer named Kitti Sarisil had hired him to deliver the Powergel.
Special Branch later said Mr Kitti was later arrested after police found several fuses and explosives during a search of a factory in Kaeng Khoi district, Saraburi.