SINGAPORE (Reuters) - Singapore has started charging visitors for coronavirus treatment, the city-state said as it reported new imported infections involving people who had traveled from neighboring Indonesia.

FILE PHOTO: Passengers arriving from Batam, Indonesia, pass a temperature screening station at the Singapore Cruise Center, following the coronavirus outbreak in Singapore March 5, 2020. REUTERS/Edgar Su

Indonesia, the world’s fourth-most populous country, reported its first virus case earlier this month and officially has just 19 infections compared to 160 in Singapore. Disease experts have questioned how many cases could be going undiagnosed in Indonesia.

Singapore’s new measures announced late Monday came into effect on March 7, when authorities said two symptomatic Indonesian travelers arrived in Singapore.

Both had reported coronavirus symptoms in Indonesia before arriving in Singapore. One had previously sought treatment at a hospital in Indonesia’s capital Jakarta.

Another case involved a Singaporean who had visited her sister in Indonesia who had pneumonia.

The health ministry did not say whether its new stance on payment for treatment related to specific cases.

“In view of the rising number of COVID-19 infections globally, and the expected rise in the number of confirmed cases in Singapore, we will need to prioritise the resources at our public hospitals,” the health ministry said in a statement.

Foreigners who are short-term visit pass holders who seek treatment for COVID-19 in Singapore need to pay but testing for the virus remains free.

Treatment of severe respiratory infections in Singapore public hospitals typically cost between S$6,000 - S$8,000 ($4,300-5,800), according to the Ministry of Health’s website.

Of 33 imported cases reported by Singapore to date, 24 involve travel to China - where the virus first surfaced late last year - three to Indonesia and the others to Italy, Britain, France and Germany.

Singapore has also determined that some of its local cases had travel history to Indonesia.

Researchers at the Harvard T.H. Chan School of Public Health, in the United States, said in a study last month Indonesia’s lack of confirmed cases at that time “may suggest the potential for undetected cases”, urging authorities there to strengthen outbreak surveillance and control.

“Are they (Indonesia) lucky or are they missing cases? It’s a little bit hard to say...but it’s certainly got people asking the question,” said Dale Fisher, a Singapore-based diseases expert who chairs the Global Outbreak Alert and Response Network coordinated by the World Health Organisation.