Prime Minister Srettha Thavisin has ordered relevant parties to ensure cadmium tailings recently found at various locations are transported back to Tak by the month's end, said government spokesman Chai Watcharonke.
Mr Chai said the order came during Wednesday's meeting between the prime minister, representatives from the Industry Ministry and executives of Bound & Beyond Plc, a company that owned the cadmium waste.
He said the company agreed to transport the cadmium tailings back to Tak and have it buried by the deadline.
A total of 3,678 tonnes of cadmium tailings were on Wednesday found at two separate locations.
The first 300 tonnes were found at a facility in Bangkok's Bang Sue area during a search made by the Environment and Natural Resources Crime Suppression Division. Police found 190 bags of cadmium tailings during the search at the premises in Soi Reangpreecha on Pracharat Road.
The inspection was made after police examined documents and found that the premises were linked to J&B Metal Co.
Wanna Kengrungruangchai, 65, who identified herself as the facility owner, faces a charge of having hazardous substance in her possession without permission, police said.
About 3,040 tonnes were found at a smelting factory owned by J&B Metal Co in tambon Bang Nam Jued in Samut Sakhon's Muang district last Thursday.
Natthapol Rangsitpol, permanent secretary for industry, on Wednesday led a team of officials to inspect another factory in Samut Sakhon, where some 3,040 tonnes of cadmium tailings were discovered.
He said the inspection found another 3,378 tonnes at the factory, bringing the total of waste found to 6,378 tonnes. He said the waste would be transported back to Tak by April 30 and buried in a landfill within 15 days.
The cadmium waste is believed to be part of 13,450 tonnes shown in a document submitted by a company in Tak seeking permission from the Tak industry office in August last year to transport them to Samut Sakhon.
The Environment and Natural Resources Crime Suppression Division reportedly summonsed two people linked to J&B Metal Co for questioning over the cadmium tailings.
Identified only as Jetsada and Wanna, the pair are scheduled to meet police on Thursday.