Chinese President Xi Jinping said the epidemic was the "largest public health emergency" since the founding of the People's Republic in 1949. "This is a crisis for us and it is a big test," he said Sunday in remarks carried by state television.
In a rare admission, at a meeting to coordinate the virus fight, he added that China must learn from "obvious shortcomings exposed" during its response. The World Health Organization (WHO) has praised Beijing for its handling of the epidemic, but China has been criticized at home for silencing early warnings from a whistleblower doctor who later died from the virus.
South Korea said it was raising its alert to the "highest" level, after the number of infections nearly tripled over the weekend to 602. The country now has the most infections outside of China, apart from the Diamond Princess cruise ship docked in Japan.
"The next few days will be crucial," South Korean President Moon Jae-in said. South Korea reported 169 new cases and three deaths on Sunday, taking the countrywide fatality toll to five.
Yonhap news agency later reported a sixth death. Around half of the country's cases have been linked to the Shincheonji Church of Jesus sect in the southern city of Daegu, where thousands of members have been quarantined or asked to stay at home.