The Chinese embassy in Kazakhstan has issued a warning about an unknown pneumonia sweeping through the central Asian country after more than 600 people died of pneumonia in June.

In an advisory issued for its citizens living in the former Soviet Bloc country, the Chinese embassy said the new disease has a fatality rate “much higher” than Covid-19.

Kazakhstan borders northwest China’s Xinjiang Uyghur Autonomous Region.

The “unknown pneumonia” in Kazakhstan caused 1,772 deaths in the first six months of the year, including 628 people in June alone, including Chinese citizens, the embassy said in a statement on its WeChat platform on Thursday.

“The fatality rate of the disease is much higher than Covid-19,” read the embassy’s statement.

It wasn’t immediately clear if Chinese officials had more information about the pneumonia or any specific reason to call it unknown: Kazakh media have only said it is pneumonia.

It was also not known if the WHO had been informed about the “unknown pneumonia”.

“The Chinese embassy in Kazakhstan reminds Chinese nationals here to be aware of the situation and step up prevention to lower the infection risks,” the embassy statement said.

According to Chinese state media, Kazakhstan’s healthcare minister said on Wednesday that the number of patients sickened by the pneumonia is two to three times more than those who have been infected with Covid-19.

The country implemented a lockdown on March 16 to contain the spread of the Covid-19 pandemic; restrictions were lifted in May but reimposed following an increase in cases.

President Kassim-Jomart Tokayev has said the country could be facing a second wave of infections.

Kazakhstan’s President Kassym-Jomart Tokayev, according to the Hong Kong-based South China Morning Post, said in a televised address on Wednesday that the situation was still serious, and it was too early to relax restrictions.

He added the country was “in fact facing the second coronavirus wave coupled with a huge uptick in pneumonia cases”.

Saule Kisikova, the health care department chief in the capital Nur-Sultan, told the news agency Kazinform: “Some 300 people diagnosed with pneumonia are being hospitalised every day.”

China, according to a Reuters report, is a major investor in oil- and metals-rich Kazakhstan and is one of the main markets for its exports, dominated by commodities. Kazakhstan also makes money from Chinese goods carried across its territory to Europe.

The Kazakhstan’s foreign ministry had summoned the Chinese ambassador in April to protest over an article on a Chinese website saying the country was keen to become part of China, the ministry said.

It was a rare move as the two countries avoid criticising each other.

It was during a lecture at a university in Kazakhstan that President Xi Jinping had first talked about the Belt and Road Initiative (BRI), his ambitious inter-continental connectivity project, in 2013.