The government on Friday reported 18 new coronavirus cases, all foreigners in Songkhla, bringing the total to 2,740 across Thailand. No additional deaths were recorded, leaving the toll at 54.

Monday's infections report marked a significant increase over the three new cases reported on Sunday. The majority of the confirmed new cases were in the southern border province of Yala, and were first reported by local health authorities on Sunday evening. 

The return to double-digit figures on Monday was due to foreigners entering the country.

The Centre for Covid-19 Situation Administration (CCSA) said all were at the immigration detention centre in Songkhla, 17 of them women.

The centre of attention is now 40 new cases found in Yala during tests done by the provincial public health office in Yala.

CCSA spokesman Taweesilp Visanuyothin said the figures will not be confirmed until testing is completed at the Medical Sciences Department at the Public Health Ministry in Bangkok.

However, there was a possibility that the Songkhla cases might be removed from the tally. Initial test results at the labs of the department in Songkhla were positive, but second tests turned negative, meaning they did not have the virus.

The ministry will send the samples to the main labs in Bangkok for accuracy and Dr Taweesilp said the results are expected within days.

"The 40 cases in Yala are not announced today," he told the press briefing.