South Korea has confirmed its first case of monkeypox virus and pledged to strengthen monitoring and response systems as it raised the alert level to "caution" for the infectious disease.

A Korean citizen, who is receiving treatment at the Incheon Medical Centre after showing symptoms while entering the country from Germany yesterday, has tested positive, the Korea Disease Control and Prevention Agency (KDCA) said. It did not provide details of the individual.

The agency raised the alert level for the infectious disease to "caution", the second of the country's four levels, upon confirmation of the virus case.

It said it will step up monitoring by designating areas that require strengthened quarantine management, mainly among people from countries where monkeypox occurs frequently.

"The KDCA has been pushing for utilising secured (monkeypox) vaccines and treatments ... and additional introduction of those, while the agency is continuously expanding its diagnostic testing capabilities," KDCA Commissioner Peck Kyong-ran said.

"Among those who have been exposed (to monkeypox virus) through physical contact with confirmed patients, those with medium or high risks will receive vaccination under their consent," Ms Peck said.

The country, however, is not currently reviewing ringvaccination for monkeypox, she added.

Earlier, KDCA reported two suspected cases of monkeypox virus, but the other case, a foreign national who entered the country on Monday after showing symptoms of blisters and sore throat, tested negative.

The agency said this patient was diagnosed with another disease without giving details.

Separately, President Yoon Suk-yeol ordered health authority to "step up quarantine management of foreign entrants at airports ... and to be fully prepared to distribute vaccines and treatments to the medical field."

Earlier in June, 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, Singapore has confirmed an imported case of monkeypox, the health ministry said.

The patient, who tested positive on 20 June, is a British man who works as a flight attendant and had flown in and out of Singapore around mid-June, the health ministry said in a statement.

He is in stable condition in a ward at the National Centre for Infectious Diseases in Singapore, the ministry said.

Thirteen close contacts of the man were identified as of yesterday, and all will be placed under quarantine for 21 days since their last contact with him, the statement added.

Contact tracing is ongoing for affected flights and for the duration of the man's stay in Singapore.

The last monkeypox case detected in the Southeast Asian city-state was three years ago.

Australia, which on May 20 reported its first case, had confirmed eight as of 10 June.

More than 35 countries where monkeypox is not endemic, including Ireland, have reported cases of the viral disease, and confirmed cases overall now exceed 2,500.