Some 242 deaths from the new coronavirus were recorded in the Chinese province of Hubei on Wednesday – the deadliest day of the outbreak.
There was also a huge increase in the number of cases, with 14,840 people diagnosed with the virus.
Hubei has started using a broader definition to diagnose people – which accounts for most of the rise in cases.
China sacked two top officials in Hubei province hours after the new figures were revealed.
Until Wednesday’s increases, the number of people diagnosed in Hubei – where the outbreak emerged – was stabilising.
But the new cases and deaths in the province have pushed the national death toll above 1,350 – with almost 60,000 infections in total.
China has been accused of suppressing the full extent of the outbreak in the past; these latest figures will raise fresh questions about the true mortality rate of the virus, says the BBC’s Nick Beake in Hong Kong.
Meanwhile, the Communist Party secretary in Hubei, Jiang Chaoliang, has been replaced by the Shanghai party chief, Ying Yong, according to state media. The party chief of the capital city, Wuhan, has also been relieved of his duties.
It is the first major change of Hubei party officials since the outbreak began.
Earlier this week, a number of health officials were “removed” from their jobs.
