Deputy Minister Chaichana Dechdecho last week exposed large-scale fraud involving hospitals and doctors issuing fake certificates to migrant workers without X-rays or blood tests, reports the Bangkok Post.
He estimated that between 200,000 and 300,000 such certificates had been issued nationwide and he ordered them all to be revoked.
Mr Chaichana said an investigation in Samut Sakhon province, where thousands of migrants from Myanmar work in the fishing industry, found a private hospital there selling health certificates without conducting proper examinations.
The hospital had registered with the Department of Employment but was still awaiting licensing from the health ministry. It had issued certificates for 13,000 workers and these are are now being annulled, said Mr Chaichana.
As well, out of 82 clinics registered with the Department of Employment, only 41 had been licensed by the health ministry, he said.
The remaining 41 were operating illegally, meaning any health certificates they issued are invalid and the workers holding them remain classed as irregular.
Additional irregularities were found in two other hospitals in Samut Sakhon covering about 30,000 workers and one in Pathum Thani covering more than 10,000 workers.
Authorities estimate that up to 300,000 workers could be affected in total.
Mr Chaichana said that under Thai law, annulments and legal action are possible, since the previously issued certificates are unlawful. Once authorities gather details on the employers and the workplaces of affected workers, the Department of Employment and the Immigration Bureau will conduct inspections and enforce compliance.
Mr Chaichana said the Medical Facilities Act stipulates a maximum penalty of one year in prison and a fine of 20,000 baht for the violations. Doctors knowingly signing false certificates may lose their licences, he added.
Provincial health authorities have also warned that issuing health documents without proper examinations could endanger public health if diseases spread undetected.