Consumer protection police raided a sausage factory in Chon Buri after children in five provinces developed a blood disorder after eating food produced there.
The raid followed information from the FDA that nine children - in Chiang Mai, Saraburi, Phetchaburi, Trang and Kanchanaburi provinces - were hospitalised after eating sausages.
They were diagnosed with a blood disorder.
Investigators first confirmed that the sausages were all made at the same factory in Chon Buri.
The police, FDA officials and health officials in Chon Buri inspected the factory and spoke to a woman who said she was the owner. Her name was withheld.
She admitted to having produced sausage products without the proper permits for about five years.
Labels of some products there matched those on the food eaten by the students who fell ill. The products had no FDA approval.
The team confiscated products worth about 700,000 baht for inspection and the factory owner was held for questioning.
Authorities also ordered the closure of the factory.