North Korea sent three of its largest cargo planes to China to pick up medical supplies to help with a spiralling Covid outbreak

Pyongyang announced its first-ever Covid cases last week and has since reported nearly two million cases of "fever" and 63 deaths as the virus tears through its unvaccinated population.

State media reports do not specify how many of the cases and deaths have tested positive for Covid, but experts say the country's crumbling health system would struggle to test and diagnose on this scale.

The outbreak was an admission that Pyongyang's rigid two-year-long coronavirus blockade, maintained at great economic cost since the start of the pandemic, had failed.

Both South Korea issued a fresh offer of aid last week, but Pyongyang has yet to respond to Seoul's offer, officials said.

And, despite no official confirmation from either side, it appears North Korea took them up: sending three Air Koryo cargo planes to Shenyang to receive medical supplies, South Korea's Yonhap News Agency reported this week.

The planes were Soviet-made IL-76 transport cargo planes capable of carrying 50 tons of freight, some of the largest planes the nuclear-armed state has, the report said.

The North chose the air route over the land "to speed up the transport of large freight", Yonhap said, citing anonymous sources.

Since declaring a "maximum emergency" over the outbreak, the North has ramped up the production of medical supplies such as antipyretic drugs and thermometers, state media reported Thursday.

Thousands of tons of salt were sent to the capital city "under an emergency order" for disinfectant production, the official KCNA reported.