Some 242 people died from the new coronavirus in the Chinese province of Hubei on Wednesday – the deadliest day since the outbreak began.
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 much of the rise in cases.
Until Wednesday’s increases, the number of people diagnosed in Hubei – where the outbreak emerged – was stabilising.
Earlier, China’s National Health Commission published its national update for Tuesday. The number of cases, 2,015, was the lowest for two weeks.
But the new cases and deaths in Hubei have pushed the national death toll above 1,350 – with almost 60,000 cases in total.
Meanwhile, the World Health Organization said it was “way too early” to predict the end of the epidemic.
“This outbreak could still go in any direction,” WHO Director-General Tedros Ghebreyesus warned.
On Tuesday top Chinese epidemiologist Zhong Nanshan said the epidemic should peak in China this month before subsiding.
The WHO has been able to track down the source of transmission in all but eight of the 441 cases of the virus outside China, its head of emergencies Michael Ryan said.
He said the apparent stabilisation in the number of new cases in China – and the slower spread of cases outside Hubei province – was reassuring.
“[That] is to a great extent due to a huge public health operation in China,” he said.
But he added: “I think it’s way too early to try to predict the beginning, the middle or the end of this epidemic right now.”
Four possible vaccines were being funded for pre-clinical development, WHO Chief Scientist Soumya Swaminathan told reporters.
“I think we will find a vaccine,” she said. “It will take some time. A vaccine cannot be made overnight.”
Dr Tedros, the WHO chief, also praised Cambodia for taking in the Westerdam, a US cruise ship that had earlier been turned away from ports in Japan, Thailand and Taiwan despite having no sick patients on board.
It was “an example of the international solidarity we have consistently been calling for”, he said.