Health authorities are asking businesses to delay bringing in workers from Myanmar, amid reports of a fresh wave of Covid-19 infections there.
Sophon Iamsirithavorn, chief of the Communicable Disease Division under the Ministry of Public Health, said the need to postpone allowing workers' entry came after an unusual spike in Covid-19 cases across the border.
On Wednesday alone, Myanmar reported 70 new confirmed infections, the highest single-day tally since the virus was first detected in the country in March.
Accumulated Covid-19 cases in Myanmar have now risen to 602, Dr Sophon said.
The hotspot is Sittwe, capital of western Rakhine state, where the authorities have now imposed a curfew from 9pm to 4am.
Meanwhile, permanent secretary for the Interior Chatchai Phromlert yesterday officially ordered the governors of the 10 provinces bordering Myanmar -- Tak, Chiang Mai, Chiang Rai, Mae Hong Son, Kanchanaburi, Phetchaburi, Prachuap Khiri Khan, Ratchaburi, Chumphon and Ranong -- to tighten security along the border and ensure strict health checks on people arriving through official crossings.
The army has stepped up security patrols in Mae Fa Luang, Mae Chan, Mae Sai and Chiang Saen districts to deter illegal border crossings, according to Col Chatri Sanguantham, chief of the Pha Muang special task force of the 2nd Cavalry Regiment.
Since Thursday, soldiers have arrested four Myanmar nationals, two men and two women, who were aged between 28 and 48, said an official source who is familiar with the matter.
The four were caught while attempting to cross the border from Thailand back to Myanmar having claimed to have travelled from Chiang Mai, said the source.
Col Chakkrit Charoenchotikan, a representative of the task force chief, said since April 18, 332 people, mostly Myanmar nationals, have been detained in 106 crackdowns on attempts to cross the border illegally in either Chiang Rai or Chiang Mai.
In Chiang Rai alone, 151 people including 83 Myanmar nationals, were detained while attempting to cross the border illegally between March 23 and Wednesday, he said.
The others detained were 54 Thai, 12 Lao and two Chinese nationals, he said.
In Kanchanaburi province, thirty-five illegal Myanmar migrants and their two drivers were arrested in Sai Yok district in the early hours of yesterday.
Two pickup trucks travelling on a local road in tambon Sri Mongkhol of Sai Yok district were stopped at around 3.40am at a checkpoint manned by soldiers, police and immigration officers.
Sunt Srianthumrong, a special lecturer on environment management with the National Institute of Development Administration, meanwhile, urged a new lockdown prohibiting all border crossings between Thailand and Myanmar.
He said that as there was a risk this second wave of Covid-19 in Myanmar could spiral out of control, Thailand should send a team of medical experts to help.