Of the six new cases, two work at Suvarnabhumi airport, Sophon Iamsirithavorn, director of the Department of Disease Control, said.
One, a 21-year-old immigration officer, fell ill on March 8, developing a fever, a runny nose and a headache. Tests at two labs showed positive for COVID-19 infection, Dr Sophon said.
The other man, aged 40, was working in a different area of the airport. He had a fever and a cough on March 7 and sought treatment at a private hospital.
Both men were in contact with foreign tourists and touched objects such as luggage or passports.
The third patient was a Thai man, 25, working for a private firm. He had a fever and muscle pains on Feb 25 and later sought treatment at a private hospital. A lung X-ray showed symptoms of coronavirus infection. He was now being treated at the Bamrasnaradura Infectious Disease Institute.
The fourth patient was a 27-year-old Thai woman who returned from South Korea. She sought treatment at a private hospital on March 8 for a fever and a runny nose. She was diagnosed with coronavirus infection and transferred to Nopparat Rajathanee Hospital on March 10.
The fifth was a 40-year-old Thai man who returned from Japan on Feb 25. While in Japan he suffered a broken wrist in an accident. On returning to Thailand he sought treatment at a private hospital in Bangkok, which found he was infected with COVID-19.
The sixth patient was a Singaporean man, 36, who runs a business in Thailand. He fell ill on March 6 with a fever and muscle pains. Lab test results on March 9 showed he was positive for COVID-19. He was now being treated at the Bamrasnaradura Infectious Disease Institute.
Dr Sophon said the six new cases brought the total number of coronavirus infections in Thailand to 59. Of these, 34 patients had been treated and discharged from hospitals. Twenty-four others remained at hospitals. One has died.
From Jan 3 to March 10, a total of 4,848 patients have been monitored - 216 from screening checkpoints and 4,632 sought treatment at hospitals. Of the 4,848 patients, 2,945 had seasonal influenza, recovered and have been discharged. They were also still being monitored. The other 1,903 remained at hospitals.
The number of global COVID-19 cases had reached 119,419 in 115 countries, two special administration zones and one cruise ship, with 4,300 deaths, including 80,788 cases and 3,158 deaths in China.