BEIJING--North Korea has announced it will impose a monthlong quarantine for all foreign visitors and others suspected to have a new virus.

The official Korean Central News Agency says the decision to extend the quarantine period to 30 days was based on researches suggesting that the incubation period of the virus could be as long as 24 days.

The report didn’t confirm the country’s previous quarantine period, but the Russian Embassy in Pyongyang said in a Facebook post earlier this month that North Korea was putting foreign visitors under a 15-day quarantine.

KCNA says: "All the institutions and fields of the state and foreigners staying in the DPRK should obey it unconditionally."

North Korea has yet to report a case of the virus, but state media reports have hinted that an uncertain number of people have been quarantined after showing symptoms. Experts say an epidemic in North Korea could be dire because of its chronic lack of medical supplies and poor health care infrastructure.