The government will likely extend the emergency decree for another month as it considers when to ease the current restrictions and allow some businesses to reopen amid the coronavirus pandemic.

Following a meeting of the Centre for Covid-19 Situation Administration (CCSA) on Monday, a source said that Prime Minister Prayut Chan-o-cha instructed the Public Health Ministry to liaise with business operators and consider allowing some to reopen, such as markets and department stores.

Entertainment venues will remain closed and the nationwide 10pm to 4am curfew is expected to be extended for at least another month, the source said, although Prayut told security officers to allow some additional types of delivery vehicles to operate during the night.

CCSA spokesman Taweesilp Visanuyothin said provinces with no virus cases were high on the list to be allowed to ease restrictions.

Nine provinces remain free of reported infections -- Ang Thong, Bung Kan, Chai Nat, Kamphaeng Phet, Phichit, Nan, Ranong, Sing Buri and Trat.

Meanwhile, Deputy Prime Minister and Public Health Minister Anutin Charnvirakul met with deans of faculties of medicine from various universities to discuss guidelines for easing the lockdown, which will be presented to the CSSA for consideration.

Speaking after the meeting, Dr Kamnuan Ungchusak, an adviser to the public health minister, said that high-risk businesses such as bars, pubs, entertainment venues and karaoke establishments will remain closed.

Medium-risk businesses, such as barber shops, hair salons, restaurants, food shops, department stores and shopping malls, would be allowed to reopen gradually, Dr Kamnuan said.

However, Dr Thira Woratanarat, a health expert at Chulalongkorn University, on Monday issued an open letter asking Prayut to think carefully.

"Restrictions should be eased only when we are actually ready. If the transmission comes back in a second wave as in Japan and Singapore, controlling the virus will be twice as hard," he wrote.