North Korea has reported 232,880 new cases of fever and another six deaths as leader Kim Jong Un accused officials of "immaturity" and "slackness" in their early handling of the Covid-19 outbreak in the unvaccinated nation.

The country's anti-virus headquarters said 62 people have died and more than 1.7 million have fallen ill amid a rapid spread of fever since late April. It said more than a million people recovered but at least 691,170 remain in quarantine.

Outside experts say most of the illnesses would be Covid-19, although North Korea has been able to confirm only a small number of cases since acknowledging an Omicron outbreak last week, likely because of insufficient testing capabilities.

A failure to control the outbreak could have dire consequences in North Korea, considering its broken health care system and its rejection of internationally offered vaccines that has left a population of 26 million unimmunised.

The outbreak is almost certainly greater than the fever tally, considering the lack of tests and resources to monitor the sick, and there's also suspicion that North Korea is underreporting deaths to soften the blow for Mr Kim, who already was navigating the toughest moment of his decade in power.

The pandemic has further damaged an economy already broken by mismanagement and US-led sanctions over Mr Kim's nuclear weapons and missiles development.

The North's official Korean Central News Agency (KCNA) said Mr Kim during a ruling party Politburo meeting on Tuesday criticised officials over their early pandemic response, which he said underscored "immaturity in the state capacity for coping with the crisis" and blamed the vulnerability on their "non-positive attitude, slackness and non-activity".

He urged officials to strengthen virus controls at workplaces and make "redoubled efforts" to improve the supply of daily necessities and stabilise living conditions, the KCNA said on Wednesday.

His comments came days after he ripped officials over how they were handling the distribution of medicine released from state reserves and mobilised his army to help transport the supplies to pharmacies in capital Pyongyang, which were made to open 24 hours to deal with the crisis.

KCNA said nearly 3,000 members of the Korean People's Army's medical units were helping the delivery of medicine to pharmacies, while more than 1.4 million officials, teachers and students in public health sectors were being deployed for checkups aimed at identifying people with symptoms so they could be quarantined.

Lacking public health tools like vaccines, antiviral pills and intensive care units that lowered hospitalisations and deaths in other nations, North Korea has been relying on finding people with symptoms and isolating them at shelters.

While raising alarm over the outbreak, Mr Kim has also stressed that his economic goals should be met. State media reports show large groups of workers are continuing to gather at farms, mining facilities, power stations and construction sites, being driven to ensure their works are "propelled as scheduled".

Before acknowledging Covid-19 infections last Thursday, North Korea had insisted on a perfect record in keeping out the virus that has reached nearly every corner of the world, a claim that was widely doubted. But its extremely strict border closure, large-scale quarantines and propaganda that stressed anti-virus controls as a matter of "national existence" may have staved off a huge outbreak until now.