South Korea is inspecting 15 suspected Wuhan coronavirus cases amid growing concerns the contagious illness may spread across the country despite stepped-up quarantine efforts. the public health agency said Tuesday.

As of early Tuesday, the total number of confirmed cases of pneumonia-like sickness stood at four, according to the Korea Centers for Disease Control and Prevention (KCDC). So far 97 people who may have been suspected of being infected by the new virus strain have been screened but released from isolation after results of the probe turned out to be negative, it said.

China, where the virus originated, reported some 2,840 confirmed cases, with the death toll reaching 81.

Outside of China, Japan, Taiwan, Thailand, Vietnam, Singapore, Malaysia, Nepal, Macao, Hong Kong, France, Australia, Germany and the United States have reported confirmed cases of the new virus.

Thailand and Hong Kong had the largest number of confirmed cases at eight each.

In regards to the fourth confirmed case of the coronavirus here that was announced Monday, the KCDC said it is in the process of determining where he visited and the people he met.

The 55-year-old South Korean man, who returned from Wuhan, the epicenter of the illness, on Jan. 20, had showed no signs of being sick upon his arrival. He visited a clinic in Pyeongtaek, 70 kilometers south of Seoul, the following day after he felt a cold, and was only placed in quarantine and monitored by the medical staff over the weekend after he ran a fever and complained of muscle cramps.

Seoul on Monday raised the country's infectious disease alert level one notch to "orange," the third highest, from "yellow."

Authorities vowed to further tighten rules on screening people and to keep more people in quarantine and under close observation.

The whole of China has been categorized as a "coronavirus risk area," and Seoul has strongly advised its citizens not to visit the central Chinese city at the epicenter of the disease.

Airports across South Korea have set up checkpoints to screen passengers from China and other countries for signs of illness, with local authorities accelerating quarantine efforts to contain the virus. (Yonhap)