Of the new cases, two female masseurs aged 38 and 49 had returned from Russia and found positive on the 13th day in state quarantine. One was asymptomatic, while another had high temperature.
The third case was a 62-year-old male waiter, who had returned from India on a flight in which 17 confirmed cases were found. He tested positive on the sixth day in quarantine and developed diarrhoea.
Meanwhile, the 110 American soldiers in Thailand for training have completed their 14-day quarantine and have all tested negative. They will undergo training from August 18 to 31, before returning home on the last day of training.
There were 60,357 people, both Thais and foreigners, under quarantine and 444 have tested positive.
As of Tuesday, the total number of confirmed cases in Thailand stood at 3,381 (444 found in state quarantine), of which 125 are under treatment, 3,198 have recovered and been discharged, and 58 have succumbed so far.
Globally, the total number of confirmed cases surpassed 22 million, up by 203,000, with 14.7 million recovered while deaths stood at 777,000. Thailand ranks 114 in the list of most cases, with the US leading with 5.6 million, followed by Brazil (3.36 million) and India (2.7 million).