North Korea's claim that "not a single person" in the country has been infected with the coronavirus is facing growing scepticism.
It has credited strict containment measures and the shutting down of its borders for this success.
But the top US military commander in South Korea has said this is "untrue", calling it an "impossible claim".
A North Korean expert told the BBC it was likely there were cases but unlikely a mass outbreak had happened.
There are currently more than one million coronavirus cases across the world and 53,069 deaths, according to a Johns Hopkins University tally.
Pak Myong-su, a director at North Korea's Central Emergency Anti-epidemic headquarters, told news agency AFP on Friday: "Not one single person has been infected with the novel coronavirus in our country so far."
"We have carried out pre-emptive and scientific measures such as inspections and quarantine for all personnel entering our country and thoroughly disinfecting all goods, as well as closing borders and blocking sea and air lanes."