Kim Jong-un has berated top officials over lapses which caused a "grave incident" related to Covid-19, North Korean state media report.

It was a rare sign of the pandemic's severity in North Korea, which previously insisted it had no Covid cases - a claim doubted by experts.

The country has closed its borders to keep out the virus.

But coupled with international sanctions, this has led to food shortages and a worsening economy.

Mr Kim previously admitted there was a "tense" food situation and told citizens to prepare for the "worst-ever" outcome, invoking comparisons to the country's deadly 1990s famine.

Earlier this week, state television aired a rare remark by a citizen commenting on Mr Kim's "emaciated" look after he appeared to have lost some weight.

In remarks reported by state news outlet KCNA, Mr Kim accused senior officials of negligence at a specially convened meeting of party leaders.

As a result, they "caused a grave incident that has caused a great risk to people and the nation's safety", according to his comments in Korean.

The report then added that several members of the party had been recalled - including one member from the powerful Standing Committee - which is composed of five members, including Mr Kim himself.

However, the report did not give any further details on the incident or identify the officials.

How bad is the situation in North Korea?

North Korea has put in place strict restrictions and state media have continually exhorted citizens to be vigilant against the virus, even warning them late last year to be wary of "yellow dust" from China. There is no known link between the seasonal dust clouds and Covid-19.

Trade with China, North Korea's main ally, has plummeted since the country sealed its borders, and some food and medicines have not been able to get through.

Aid organisations have warned of a serious food and economic crisis.

Reports have emerged in recent months of soaring food prices, as well as deaths by starvation and increased numbers of people begging for food.

The latest state media report was an indication of "deteriorating" health conditions inside North Korea, said Dr Leif-Eric Easley, associate professor of international studies at Ewha Womans University in Seoul.

"Mr Kim will likely find scapegoats for the incident, purging disloyal officials and blaming their ideological lapses," he said.

"This may provide Pyongyang justification for demanding that citizens hunker down more, but it could also be political preparation for accepting vaccines from abroad."