The confirmed Covid-19 caseload in Thailand soared by 382 on Monday, 360 of them migrant workers from Myanmar linked to a wholesale shrimp market in Samut Sakhon, the province bordering Bangkok on the southwestern side.
The spike in infections followed the 576 new cases recorded on Sunday. Monday's rise was expected because of ongoing, intensive testing of thousands of migrant workers in the province's fishing industry, mainly in the areas locked down since Saturday night.
The new infections raised the accumulated total in Thailand since the start of the outbreak to 5,289, according to the Centre for Covid-19 Situation Administration (CCSA).
CCSA spokesman Taweesilp Visanuyothin said additional cases linked to the Central Shrimp Market in tambon Mahachai are expected to be announced in an update from the Public Health Ministry on Monday afternoon.
"New reports keep flowing in. There will be more new cases," Dr Taweesilp said.
The spokesman urged all workers from Myanmar to come out to be tested, including those who sneaked across the border into Thailand. Illegal migrants will not be punished, he said.
"We emphasise only health measures, not immigration regulations," he said.
The issue of illegal Myanmar workers hiding from health officials was raised in talks between Prime Minister Prayut Chan-o-cha and the ministry's team led by Public Health Minister Auntin Charnvirakul. National Security Council secretary-general Nattaphon Narkphanit also attended the talks.
Dr Taweesilp said a field hospital of 100 beds will be set up in the sealed area in Samut Sakhon in order to contain the spread of Covid-19. "We will not let the patients move out of the area," he said.
About 1,000 people regularly come to the Central Shrimp Market, the epicentre of the new outbreak, to buy shrimp for wholesale and retail sales in Samut Sakhon and other provinces.
The CCSA spokesman said authorities are tracing all of them.