The Civil Aviation Authority of Thailand (CAAT) will begin talks on the resumption of international services with airline representatives on Tuesday, according to director-general Chula Sukmanop.

Priority will be given to business trips, with tourists from paired "travel bubble" countries being allowed in later, he said, adding that investors are ready to absorb costs related to the Covid-19 control measures such as a quarantine programme.

Mr Chula said he called in all airlines that operate international flights for discussions on measures to be implemented to prevent the spread of Covid-19.

The measures include social distancing on planes and at airports, guidelines for inflight food services and quarantine areas aboard planes for passengers who fall sick during flights, he said.

According to Mr Chula, international flights would first resume to serve people who have to supervise businesses in Thailand or overseas. They would have to be prepared for quarantine and possible medical treatment costs, he said.

The CAAT director-general said he does not expect the travel bubbles for foreign tourists proposal would be ready for implementation next month as there are several factors to be considered, including the Covid-19 situation in other countries and the cost-effectiveness of flight routes.

The CAAT has prolonged its ban on inbound and outbound commercial flights until June 30.

However, certain flights are still allowed to land, such as those involving state or military aircraft, Covid-19 humanitarian aid, medicine, emergency landings and the repatriation of Thais from overseas who are subject to a 14-day quarantine.

Meanwhile, Don Mueang airport expects to see a steady increase in passengers now that the curfew is lifted.

Currently, Don Mueang airport handles 148 flights per day.