Leader Kim Jong Un has declared victory in North Korea's fight against the coronavirus and ordered an easing of "maximum emergency" measures imposed in May, official media reported Thursday, with his sister suggesting he may have caught the virus himself.

Kim made the announcement at a meeting with health officials and scientists on Wednesday, praising their contributions to "successfully defusing the serious epidemic spread crisis" and defending the country's "social system which is the best in the world," according to the Korean Central News Agency.

North Korean leader Kim Jong Un attends a national meeting of reviewing the emergency anti-epidemic work in Pyongyang on Aug. 10, 2022. (KCNA/Kyodo)

The leader's sister, Kim Yo Jong, delivered a speech at the meeting and said her brother was "seriously ill with a high fever" but he "could not lie down for even a moment" as he led the country's anti-epidemic efforts, KCNA said.

The sister, who is vice department director of the Central Committee of the Workers' Party of Korea, blamed leaflets and other "dirty objects" sent by balloons from North Korean defectors in South Korea for causing the virus outbreak, according to the news agency.

"We can no longer overlook the uninterrupted influx of rubbish from South Korea. This is just an unethical crime," she said. "We must counter it toughly."

North Korea disclosed its first case of the virus on May 12 after claiming to have had no COVID-19 infections for more than two years. Its daily number of what it called "fever" cases peaked at over 390,000.

The country, which is believed to lack sufficient COVID-19 testing capacity, has reported no additional suspected cases since July 29. Its authorities have reported about 4.77 million fever cases since late April, with 74 patients dying.

North Korea said it "restored the complete stability in the anti-epidemic work in a short period," and touted the achievement as "a miracle unprecedented in the world's public health history," according to the news agency.

Pyongyang claims people who touched "alien things" near the border with South Korea were the first to be infected with the novel coronavirus.

It has long accused Seoul of failing to prevent activists from launching balloons across the border containing messages denouncing the North Korean leader.

"If the enemy persists in such dangerous deeds as fomenting the inroads of virus into our republic, we will respond to it by not only exterminating the virus but also wiping out" South Korean authorities, Kim Yo Jong was quoted as saying at the meeting.

Seoul has dismissed Pyongyang's claims, saying there is no possibility that a coronavirus outbreak in the North is connected with such materials sent over the border.

South Korea's Unification Ministry expressed strong regret Thursday over North Korea's "insolent and threatening remarks based on repeated groundless claims" regarding the origin of the coronavirus outbreak in the North, according to Yonhap News agency.

South Korea's spy agency, meanwhile, has cast doubt on whether Pyongyang's daily reports truly reflect the scale of COVID-19 infections in the neighboring country.