Thailand has 143 new coronavirus cases, bringing the total number of cases since the outbreak began to 1,388, the Centre for Covid-19 Administration said on Sunday.
Taweesin Wisanuyothin, the spokesman for the centre and the Public Health Ministry, said the country also recorded one new fatality, bringing the total number of deaths to seven.
The latest victim was a 68-year-old man from Nonthaburi who had attended a crowded boxing match at Lumpinee Boxing Stadium where there had been a cluster of infections, Dr Taweesin said.
The match was held at the army-run stadium on March 6. About 2,500 people attended the event that day.
The number of new cases was a significant jump from the 109 recorded on Saturday.
Prime Minister Prayut Chan-o-cha, who chairs the centre, was in talks with other officials at Government House to discuss additional measures as the number of new infections and deaths escalated.
The government on Saturday said the increasing number of infections was due to people failing to practise social distancing.
Twenty-two revellers at a drug party in Chiang Rai were arrested on Saturday for gathering in defiance of the nationwide Emergency Decree.
Authorities have imposed a lockdown in the southern provinces of Pattani, Yala and Narathiwat, while authorities on the resort island of Phuket have asked people to stay home from 8pm to 3am in a new restriction on movement to curb the spread of the coronavirus. Phuket recorded six new cases on Saturday, four in the Patong area, and another six new cases on Sunday, all linked to Patong.