North Korea is further tightening quarantine measures against COVID-19 amid the emergence of a new variant called the "mu" strain.

The North's state-run Korean Central News Agency on Friday mentioned the mu strain, saying that yet another dangerous and highly transmissible variant is causing global concern.

The report said the new strain first identified in Colombia in January has since led to cluster outbreaks in South America and Europe, while cases are also reported in Japan.

The KCNA said a politburo meeting of the Workers' Party held Thursday also discussed North Korean style anti-virus measures and enhancing capabilities of quarantine experts.

The ruling party newspaper Rodong Sinmun on Saturday repeated the call, saying the country must not lower its guard and stay vigilant.

The paper called on scientists and engineers in the health sector and all related fields to actively adopt advanced technology and continuously explore and introduce North Korea's own quarantine methods. 

The global vaccine sharing program COVAX had assigned one-point-nine million doses of the AstraZeneca vaccine for North Korea, but the regime has taken few steps to accept the shipment. It also rejected nearly three million doses of China's Sinovac vaccine, saying they should be sent to other countries instead.