Thailand has 11 more patients infected with the coronavirus, all friends who went out drinking together despite some being ill, the Public Health Ministry said on Thursday.
The ministry said the new patients were found infected in a cluster for the first time since Covid-19 hit the country.
The latest report brought the total of the local patients to 70, it added.
Thirty-four people have been discharged with 24 still in hospital, one of them in serious condition at Bamrasnaradura Infectious Diseases Institute.
All 11 new patients are Thai, five of them men aged 25-38, according to the ministry. They were among a group of 15 who went out drinking together last month. Four of them tested negative.
Sukhum Karnchanapimai, permanent secretary for public health, told reporters some members of the group met with visitors from Hong Kong on Feb 21 and developed a fever, headache and cough on Feb 25.
Despite feeling unwell, they went out for drinks with their close Thai friends twice, on Feb 27 and 29, drinking from the same glasses and sharing cigarettes, and then went to hospitals on March 4, Dr Sukhum said.
The four who were not infected with the virus said they did not drink or smoke, he added.
The ministry said the patients not "super spreaders". Lab tests on samples from about 70 family members all proved negative.
Chulalongkorn University posted a message denying that one of the patients was a student there.