Three more infections were found among tourists who arrived under the Phuket Sandbox programme, raising the total to six, provincial health office chief Kusak Kukiatikoon said on Monday.
Dr Kukiat said the figures were from a report reaching his office on Sunday.
The three new cases were a 45-year-old Myanmar national who arrived in a family of seven, a 28-year-old African who came with two friends, and a 13-year-old Swiss who arrived in a family.
People who had been in close contact with them had been under a disease control process, he said.
Of the total 3,917 tourists who had arrived in Phuket from July 1-10, six of them had tested positive for Covid-19 – one from the United Arab Emirates, three from Myanmar, one from Africa and one from Switzerland, Dr Kukiat said.