The government on Wednesday reported 250 new Covid-19 cases - 241 local infections, eight quarantined arrivals and one illegal Myanmar migrant - raising the total to 6,690.
Dr Taweesilp Visanuyothin of the Centre for Covid-19 Situation Administration said nine were linked to Samut Sakhon, showing a decline in new cases from the province's the Central Shrimp Market.
Of these nine, four were in Samut Sakhon, two in Bangkok and one each in Ayutthaya, Ranong and Nonthaburi.
Testing found two new cases among migrant workers.
Meanwhile, 198 new cases were under investigation including 108 in Chon Buri, 53 in Rayong, 17 in Nonthaburi, 12 in Samut Sakhon, seven in Chanthaburi and one in Trat.
"These cases were likely linked to gambling," Dr Taweesilp said.
Twenty-nine others had visited crowded and entertainment places or were in at-risk occupations. Of these, 15 were in Bangkok, mostly elderly people, five in Nakhon Pathom, three each in Phetchaburi and Saraburi and one each in Nakhon Nayok, Nonthaburi and Samut Prakan.
Investigation confirmed three new cases were linked to illegal gambling in Rayong province. They were found in Amnat Charoen, Ayutthaya and Rayong.
From Dec 18-30 new cases were reported in 48 provinces, the majority of the country, Dr Taweesilp said.
New cases who were quarantined arrivals came from the United States, Kuwait, Australia, Kenya and Russia. The single infected illegal Myanmar migrant had been repatriated.
Of the total 6,690 local cases, 4,212 (62.9%) had recovered, including two discharged over the previous 24 hours, and 2,417 were receiving treatment. The death toll was unchanged at 61.
