The government reported 39 new Covid-19 cases, 28 locally transmitted and 11 imported, raising the accumulated total since the start of the pandemic to 28,773.
No additional deaths were recorded, leaving the toll at 94.
Apisamai Srirangson, assistant spokesperson for the Centre for Covid-19 Situation Administration, said 16 new cases were confirmed at hospitals and 12 others were found through active case-finding in communities.
Bangkok logged 15 new cases, just over half of the daily increment. Nine of them were found at hospitals and six others in communities.
Samut Sakhon province found 10 new cases, five at hospitals and five in communities.
Maha Sarakham, Ratchaburi and Kalasin provinces recorded one case each.
The northeastern province of Kalasin recorded its first-ever Covid-19 case – a Thai saleswoman at a department store, Dr Apisamai said.
On March 22, the 35-year-old woman visited a friend who sold goods at a market in Bang Khae district of Bangkok. She returned to Kalasin on March 24 via a Vietjet flight to Khon Kaen province and then a van to Kalasin.
Last Thursday she developed a fever, a cough, a runny nose and fatigue. On the following day she learned that her vendor friend had contracted Covid-19. Her own test returned positive on Saturday.
It was worrying that the new case happened after an inter-provincial visit, since domestic travel is set to soar over the upcoming Songkran holidays, Dr Apisamai said.
Infections linked to the Bang Khae market cluster have now spread Covid-19 to 11 provinces, she said.
The 11 imported cases were quarantined arrivals from India (3), the United Arab Emirates (2) and one each from Germany, Ghana, Russia, Ivory Coast, Ukraine and Egypt.
Of the 28,773 total cases, 27,313 (95%) have recovered – including 74 discharged over the past 24 hours – leaving 1,366 at hospitals, including six patients on ventilators and another six severely ill.
Global Covid-19 cases rose by 485,732 in 24 hours to 127.76 million. The worldwide death toll went up by 6,789 to 2.80 million. The United States had the most cases at 30.96 million, up 44,096.