North Korean leader Kim Jong-un / Yonhap

There is no sign that North Korean leader Kim Jong-un has been inoculated against the coronavirus and his country hasn't received any foreign vaccines, South Korea's spy agency said Thursday.

The National Intelligence Service told lawmakers in a closed-door briefing that it hasn't detected any information that North Korea has acquired vaccines, according to Ha Tae-keung, one of the legislators who attended the session. He quoted the NIS as saying there were no signs that Kim has been inoculated.

COVAX, the U.N.-backed program to ship COVID-19 vaccines worldwide, said in February that North Korea could receive 1.9 million doses in the first half of the year. But the shipment hasn't been made, and there have been no reports that North Korea has tried to secure vaccines elsewhere for its 26 million people.

The NIS has a mixed record in reporting developments in North Korea, one of the world's most secretive countries. Some non-government experts have speculated that Kim and his top deputies may have received vaccines imported through unofficial channels.

Another lawmaker, Kim Byung-kee, quoted the NIS as saying that North Korea's government is trying to dispel any expectations among ordinary citizens that they will receive vaccines from abroad and is instead urging them to boost their anti-virus vigilance.

He said North Korea is building guard posts and concrete structures along its border with China to prevent illegal border crossings as part of its anti-virus steps. He said the lawmakers were told that North Korea isn't even allowing the entry of diplomats from China, its main ally and aid benefactor.

Kim Jong-un recently berated top officials for ''crucial'' failures in coronavirus prevention that he said caused a ''great crisis.'' But his government continues to claim a perfect record in fending off the virus from its territory, an assertion that is widely questioned by outside experts.

The World Health Organization said last week that North Korea has reported to it that it has tested 31,794 people for the virus through June 24 and that all were negative.