Untraceable coronavirus cells in three countries coupled with clusters in a remote part of Italy are red flags that the illness could be spreading uncontrollably, health experts warned Saturday.

The cells that couldn’t be tracked to a source popped up in South Korea, Iran and Singapore, leading the World Health Organization to call for a stricter approach to containing the virus.

WHO officials have held off declaring the virus a pandemic — the spread of a disease to two continents — although doctors have started mentioning the word as the number of deaths and confirmed cases soar.

Worldwide, the death toll from the virus stands at 2,362 and the cases total 77,968.

WHO’s top leader spoke Saturday to the African Union, making clear his worry about the spread of the disease — particularly across the Middle East.

“The window of opportunity is narrowing” to contain the infection, said WHO Director-General Tedros Adhanom Ghebreyesus. “We have to prepare . . . because this outbreak could go any direction — it could even be messy.”

An untraceable case in Iran led to more than two dozen others falling ill. The number of deaths hit five — four in the past two days alone.

Later in the day, Iraq reported its first case — a student who had returned from Iran, a medical source told Anadolu Agency, a Turkey-based news outlet.

Other new hot spots:

n Italy locked down 10 northern towns Saturday after a 78-year-old man died and the number of new confirmed cases jumped to 20 — 15 in the Lombardy region. The 15 in Lombardy had gone to the same bar and had the same group of friends. Officials even canceled Ash Wednesday church services.

n South Korea asked the 2.5 million residents of Daegu, its fourth-largest city, to stay indoors after more than 1,000 members of a church there showed flu-like symptoms.

The number of cases skyrocketed by 229 — 200 in Daegu — bringing the total to 433. The death toll stands at three; the latest victim was a man in his 40s who died at home and posthumously tested positive.

In the US, the fear of a pandemic spurred the FBI to order $40,000 in face masks and hard sanitizer. The agency gave manufacturers 3M and PDI Healthcare only a week to fill the order.

US health officials have confirmed 35 confirmed coronavirus cases nationwide but no deaths.

And the epicenter of the outbreak, China, has a new crisis to deal with — hundreds of animal deaths that Communist Party officials blamed on “massive disinfecting efforts.”

Additional reporting by Sara Dorn, Jon Levine and Paula ­Froelich