The shutdown of Hong Kong airport could cost Thailand Bt1.4 billion in lost income, Kasikorn Research Centre said.
The centre estimates the Thai tourism industry will be adversely hit if flights from Hong Kong are disrupted for more than seven days.
This is high season for Hong Kong tourists to visit Thailand because school closes for summer in August there.
Thailand has been getting anything from 4,200 to 5,000 visitors from Hong Kong daily this month.
“If the airport is shut for seven days, we will lose up to 30,000 visitors,” the research centre warned.
Last year, 1.02 million people from Hong Kong visited Thailand, representing 2.65 per cent of the market share, resulting in an income of Bt42 billion.
Flights from Hong Kong were cancelled for a second day when protesters took over the airport on Tuesday afternoon after it had opened earlier in the day to start rescheduling flights.