Thailand has nine new local coronavirus infections, the biggest one-day rise in local transmissions in more than seven months, health officials said on Saturday.
The nine cases are connected to a shrimp market in Samut Sakhon province, near Bangkok, where four infections were reported on Friday, officials told a briefing.
The cases started with a 67-year-old woman, who sells shrimp in the market, who was confirmed to have the infection before three of her family also tested positive.
There is no need for a lockdown yet but steps will be taken if cases keep rising, Taweesin Wisanuyothin, a spokesman for Thailand's COVID-19 taskforce, told the conference.
"If the number of cases won't come down tomorrow or the day after and become a cluster with unfound origins, we will choose measures from light to strong to handle it," he said.
Minister Anutin Charnvirakul said late on Friday the situation was not worrisome and more than 2,000 people in the area had been tested and more tests would be conducted.
Local cases have largely been found in people observing quarantine after having been in close contact with an infected person. Most of Thailand's recent cases have been imported.
Thailand has kept infections at just 4,331 cases and 60 deaths, but its tourism-reliant economy has suffered from a travel ban imposed since April to curb the outbreak.
The country on Thursday further eased restrictions to allow more foreign tourists to return.
The government predicts about 8 million foreign tourists in 2021 after 6.7 million expected this year. Last year's foreign visitors were a record of nearly 40 million..