From Sunday on the government will extend the requirement of medical certificates and health insurance to cover all visitors to the country regardless of nationalities to curb the spread of the coronavirus.

Travellers to Thailand have to now show authorities a health certificate, issued no more than 72 hours before travelling, confirming that they have been tested and are free from the virus. They must also present an insurance policy showing minimum coverage for coronavirus of not less than US$100,000.

This measure was previously a requirement for places the government classified as "disease infected zones" — China, South Korea, Hong Kong, Macau, Italy and Iran.

"We are blocking infection from coming into the country. That is why people need medical certificates and health insurance to enter Thailand," , Prime Minister Prayut Chan-o-cha said on Thursday.

"This will now include all countries to minimise infection so we can control it," he said.

Since people cannot get tested for the virus in most places at the moment due to the high costs and shortages of test kits, the requirement is in effect a travel ban although the government stopped short of describing it as such.

Public Health Minister Anutin Charnvirakul also said the measure should discourage foreigners from travelling to Thailand. "We are enforcing strict measures so that it will be very difficult for them to come here."

The Interior Ministry will also close all borders, he added, without elaborating.

The Civil Aviation Authority of Thailand also said it requires Thai returnees to show fit-to-fly health certificates and a letter acknowledging their return issued by a Thai embassy, a Thai consulate-general or the Foreign Ministry.