Untraceable coronavirus cells have emerged in three countries — and health officials say the elusive strands could be the first sign that the virus is spreading at an uncontrollable pace.

Doctors are unable to identify the source of coronavirus clusters in South Korea, Singapore and Iran, the World Health Organization said Saturday, urging a stricter approach to containing the virus.

“A number of spot fires occurring around the world is a sign that things are ticking along, and what we are going to have here is probably a pandemic,” said Ian Mackay, a researcher at Australia’s University of Queensland.

Doctors began floating fears of a pandemic — which occurs when a disease spreads to two continents — on Friday as two more died in Iran, the number of cases in South Korea doubled, and Italy saw its first death.

In Iran, an untraceable case that’s spread to 28 others is believed to have popped up in the city of Qom.

Hundreds of new cases detected in South Korea were sparked by a member of a church of 9,000 in the city of Daegu, but doctors have been unable to pinpoint the origin.

Doctors fear the spread could quicken and widen if they are unable to identify all those infected and get them into quarantine. Making matters worse, coronavirus symptoms are often so mild that a spreader could be unaware they are infected.

People are unlikely to die from the mild cases, “but it’s really bad news if you are trying to stop a pandemic,” Mackay said of the subtle symptoms.

An official with the World Health Organization warned Saturday that “the window of opportunity is narrowing” to contain the virus.

“We have to prepare at the same time for any eventualities, because this outbreak could go any direction — it could even be messy,” WHO Director-General Tedros Adhanom Ghebreyesus said.