The Public Health Ministry on Friday reported 50 new local Covid-19 cases -18 of them linked to boxing stadiums and 12 to contact with previous patients - raising the total to 322.
Dr Suwannachai Wattanayingcharoenchai, director-general of the Disease Control Department, divided new cases into two groups.
The first group of 41 involved those in contact with previous patients or premises with previous patients. They consist of 18 people who visited boxing stadiums and five visiting entertainment places, 12 people in contact with previous patients and six attendees at religious ceremonies in Malaysia.
The second group has nine cases - four returnees from other countries, two who worked or lived in crowded places or worked with foreigners, and three whose cases were under investigation.
“The Public Health Ministry is finding more patients who were in contact with the boxing stadium group and the entertainment place group. Likely there are many people who had contact and they may fall sick within 14 days,” Dr Suwannachai said.
“Importantly these people are not being strict enough about self-isolation and are transmitting the disease to many people in their proximity.
"This is the creation of another generation of high-risk people. They must be monitored for 14 more days. The disease will be transmitted through generations in big numbers due to their failure to follow advice from the Public Health Ministry,” he said.
Dr Suwannachai said Covid-19 cases were reported in 24 provinces, with the highest density in Bangkok, followed by Samut Prakan, Chiang Mai and Pattani.
He asked people living in areas with many patients - greater Bangkok and other provinces - not to return to their home provinces and strictly follow home quarantine, take leave or work from home, stay at least two metres from others and use personal sets of appliances and food servings".
He particularly referred to staff and visitors at boxing stadiums and entertainment venues.
Of the 322 local cases, 278 were being treated at hospitals, 43 recovered and were discharged from hospitals, and one had died, he said. The recovered cases included a 36-year-old Frenchman who was discharged from the Central Chest Institute of Thailand in Nonthaburi province on Friday.
Patients under investigation numbered 8,729, 62% of whom recovered and had suffered mainly from seasonal flu.