The Chinese Embassy in Kazakhstan is warning an "unknown pneumonia" sweeping through the country is deadlier than COVID-19.
In the first six months of 2020, 1772 people have died in the country from the mystery disease, including 628 people in June alone.
Cases of the illness are currently spiking in several provinces, local media reports.
On Friday the embassy in Kazakhstan, which borders China, issued a warning to Chinese citizens saying "the fatality rate of the disease is much higher than COVID-19".
"The Chinese embassy in Kazakhstan reminds Chinese nationals here to be aware of the situation and step up prevention to lower the infection risks," they said, as reported by the South China Morning Post.
The embassy described the illness as an "unknown pneumonia" but Kazakhstani officials and media have only called it pneumonia.
The embassy said organisations including Kazakhstan's health department are studying the virus.
Kazakhstan implemented a lockdown in March to tackle the spread of COVID-19. While it was lifted in May, it has been reimposed in some areas after the increase in pneumonia case.
President Kassym-Jomart Tokayev said the country is "facing the second coronavirus wave coupled with a huge uptick in pneumonia cases", according to Russian news agency Tass.