China has stopped publishing daily COVID-19 data, adding to concerns that the country's leadership may be concealing negative information about the pandemic following the easing of restrictions.

China's National Health Commission said in a statement that it would no longer publish the data daily beginning Sunday and that "from now on, the Chinese CDC (Center for Disease Control and Prevention) will release relevant COVID information for reference and research." The NHC did not say why the change had been made and did not indicate how often the CDC would release data.

China is experiencing a surge in new cases since restrictions were eased. In China's eastern Zhejiang province alone, the provincial government said it was experiencing about 1 million new daily cases. Meanwhile, Bloomberg and the Financial Times reported on a leaked estimate by top Chinese health officials that as many as 250 million people may have been infected in the first 20 days of December.

Despite the surge in cases, China has suspended most public testing booths, meaning there is no accurate public measure of the scale of infections across the country.

Last week, Chinese health officials also defended the country's high threshold for determining whether a person died from COVID-19. Currently, China excludes anyone infected with COVID who died but who also had preexisting health conditions, and in the four days leading up to the health commission's decision to end publishing data, China reported zero COVID deaths.

Last week, the World Health Organization warned that China may be "behind the curve" on reporting data, offering to help with collecting information. WHO Health Emergencies Program Executive Director Michael Ryan said, "In China, what's been reported is relatively low numbers of cases in ICUs, but anecdotally ICUs are filling up."

Airfinity, a British health data firm, estimated last week that China's true COVID figures were a million infections and 5,000 deaths a day. On Friday, a health official in Qingdao, in China's eastern Shandong province, said the city was seeing around 500,000 new COVID cases a day. The report was shared by news outlets, but then seemed to have been edited later to remove the figures. There has also reportedly been surge in need for crematoriums.

China had earlier this month scrapped many of its very restrictive COVID measures following protests around the country that were critical of leadership. The demonstrations were sparked by deaths in a fire at an apartment block in the city of Urumqi in Xinjiang province, which killed at least 10 people. Some said the deaths could have been prevented if restrictions were less strict.

In a recent briefing, the University of Washington's Institute of Health Metrics and Evaluation forecast up to 1 million deaths in 2023 if China does not maintain social distancing policies.

Many are concerned that celebrations during next month's Lunar New Year in China could become superspreader events.

NPR's Emily Fang contributed to this report.