SEOUL, May 12 (Reuters) - South Korea's presidential office expressed willingness to provide humanitarian assistance to North Korea after it officially confirmed the first outbreak of COVID-19 in Pyongyang on Thursday, South Korea's Newsis reported.

The North's official KCNA said earlier in the day a sub-variant of the highly transmissible Omicron virus has been detected in samples collected on Sunday.

North Korean leader Kim Jong Un has ordered all cities and counties to "strictly lock down" their regions to prevent the spread of the virus, KCNA said.

(Reporting by Soo-hyang Choi; Editing by Tom Hogue)