By Isobel van Hagen and Stella Kim and Nancy Ing, NBC News

North Korea's leader Kim Jong Un called an emergency meeting after imposing total lockdown measures on the city of Kaesong when a person there was found with suspected coronavirus symptoms, state media reported Sunday.

It would be the first confirmed case in the secretive communist state if the person tests positive. North Korea has repeatedly said it is free of the virus, a claim questioned by outside experts.

At the meeting, Kim called the moment, "a critical situation in which the vicious virus could be said to have entered the country," the North’s official Korean Central News Agency reported.

The lockdown in Kaesong, a city with an estimated population of 200,000, located just north of the heavily fortified land border with South Korea, began Friday afternoon, KCNA reported.

The suspected virus patient is a runaway who fled to South Korea three years ago before illegally crossing the border into the North early last week, the agency added.

An outbreak in North Korea could cause dire consequences because of its fragile public health care infrastructure and chronic lack of medical supplies, experts have warned.

Across the border, China reported 46 new COVID-19 cases on Sunday, the highest daily tally in more than a month.

It came as the number of confirmed virus cases worldwide topped 16 million on Sunday, according to Johns Hopkins University data. The U.S. leads the count with 4.1 million, followed by 2.3 million cases in Brazil and 1.3 million in India.

Elsewhere, Europe, which has slowly re-opened its borders after months of strict lockdowns across the continent, is experiencing fears of new hot spots as summer vacationers begin to travel.

Some of Spain’s summer venues, including nightclubs, bars and beaches, are facing new restrictions. The northeast region of Catalonia is also home to two virus hotspots, prompting authorities in Barcelona to tighten restrictions that were relaxed only a month ago.

The spike in once badly-hit Spain prompted Britain — the country with the highest death toll in Europe — to put the country back on its unsafe travel list.

Taking vacationers — including British Transport Secretary Grant Shapps — by surprise, the U.K.'s government announced Saturday that travelers arriving in the U.K. from Spain must now quarantine for 14 days.

The abrupt decision came after Spain reported over 900 new daily infections on Thursday and Friday.

Coronavirus infections in France have also crept up, with over 1,000 news cases recorded on both Friday and Saturday.

Health authorities warned that the country is going backward in its battle against the pandemic, which has killed more than 30,000 people in the country.

“We have thus erased much of the progress that we’d achieved in the first weeks of lockdown-easing,” health authorities said, adding that the French appear to be letting down their guard during their summer vacations.

However, Germany authorities were confident enough to send a cruise ship out to sea with 1,200 passengers for a weekend test of how the cruise industry can begin to resume.

Occupancy was limited to 60 percent so passengers could keep their distance from one another, but even that level was not reached.

However, in other parts of the world the pandemic still appeared to have the upper hand.

Vietnam on Sunday reimposed restrictions in one of its most popular summer beach destinations in Da Nang after a second person tested positive for COVID-19. They were the first locally transmitted cases in the country in over three months.

South Africa also reported more than 12,000 new confirmed cases on Saturday, according to the Africa Center for Disease Control, as the total reaches 434,200 with 6,655 deaths. The country makes up well over half the confirmed cases on the African continent.

In the United States, Texas — which has been struggling with the virus — was hit by Storm Hanna which could make tackling its outbreak more difficult.

Australia’s Victoria state has recorded 10 deaths overnight from COVID-19, its highest daily toll amid a continuing surge in cases. There are 459 new infections, the 21st straight day of triple-figure increases.

The Associated Press contributed to this report.