The first group of foreigners that have registered for 14-day state quarantine include those with work permits, investors and business executives, said Taweesin Wisanuyothin, spokesman for the government's Centre for COVID-19 Situation Administration.

The new measures will be subject to approval by the government's task force that meets on Monday, he said, adding that medical tourists would also be allowed entry.

The Thai aviation regulator has banned international commercial flights up to the end of June, but has said some business travel could resume in July.

"There will not be a complete opening of skies any time soon because the crisis is still going on globally, but arrangements can be made for certain foreign travel," Taweesin told Reuters.

Short-term business travellers will be required to have a certificate showing they are free of the coronavirus, health insurance and to allow medical personnel to monitor them while in Thailand.

Travellers, however, may find it difficult to obtain virus-free certification due to limited testing and flights to Thailand because the pandemic has brought global air travel to a virtual standstill, with many airline fleets grounded.

Tourists from countries with "travel bubble" arrangements will be allowed to travel in August, but they will be limited to a certain space in what the government calls "villa quarantine".

Foreign arrivals this year are expected to be only around 8 million people, down from last year's record of 39.8 million, the central bank had said.

Thailand has so far recorded 58 deaths related to COVID-19 among 3,157 infections, of which 3,026 patients have recovered.

The government on Wednesday also announced that schools, bars and massage parlors would also re-open next month, but with strict health guidelines.