BANGKOK (BLOOMBERG) - Thailand said all arriving Chinese tourists must provide medical certificates stating that they are healthy and free of infection from the novel coronavirus.

This measure is being implemented in the wake of the World Health Organisation's decision to call the virus outbreak a global health emergency, the government said in a release dated Feb 1.

Chinese visitors spent almost US$18 billion (S$24.5 billion) in Thailand last year, more than a quarter of all foreign-tourism receipts.

With China banning outbound group tours to fight the virus, Thailand's tourism industry - which makes up about 21 per cent of the economy - is taking a severe knock.

Reduced travel from China alone could result in 50 billion baht (S$2 billion) of lost tourism revenue, the Thai Tourism Ministry estimated.

The spread of the coronavirus beyond China has also affected domestic tourism in Thailand, which has recorded more infections than anywhere but China with 19 cases. Thailand announced its first case of human-to-human transmission on Jan 31.

Shopkeepers in Phuket said that had left Thai tourists wary of venturing out to join what should have been an annual festival on Walking Street in the heart of the town.