One of the people, who reportedly showed potential symptoms of the infectious disease while entering the country via Incheon International Airport, has been admitted to Incheon Medical Centre, Yonhap said.

Diagnostic tests were being conducted on the suspected cases, it added, citing the Korea Disease Control and Prevention Agency.

The health ministry declined to comment on the report.

Earlier this month, South Korea designated monkeypox as a second-degree infectious disease, according to its four-tier system, with 22 contagious diseases including COVID-19, cholera and chickenpox being included in the same category.

Meanwhile, authorities in the United Kingdom are recommending gay and bisexual men at higher risk of exposure to monkeypox should be offered a vaccine as the outbreak of the disease gathers pace in Europe.

Although anyone can contract monkeypox, data from the outbreak suggests the majority of transmission is occurring within the sexual networks of gay, bisexual and other men who have sex with men, according to the UK Health Security Agency (UKHSA).

A person's eligibility would be similar to the criteria used to assess those eligible for pre-exposure prophylaxis (PrEP) - medicine taken by people at risk of contracting HIV from sex or injecting drugs, the UKHSA said on Tuesday.

Doctors may advise vaccination for someone who, for example, has several partners, participates in group sex or attends "sex on premises" venues, the agency said.

Initially, UKHSA had recommended only close contacts of cases, including healthcare workers, be offered the vaccine Imvanex.

Bavarian Nordic's vaccine is approved for smallpox in Europe but has been used off-label in response to monkeypox cases.

More than 2500 cases of monkeypox have been reported from more than 35 countries outside of Africa, where the virus is endemic.

As of June 20, there were 793 laboratory confirmed cases in the UK.

The outbreak has triggered concern since the virus is rarely seen outside central and west Africa - and the majority of the recent more widely spread cases are not related to travel to the continent.

Scientists are scrambling to understand what is driving the current outbreak, its origins and whether anything about the virus has changed.

The monkeypox virus is understood to spread through close contact with an infected person, who may shed the virus via its hallmark skin lesions or large respiratory droplets.

Australian Associated Press