The head of the World Health Organization said on Wednesday that the largest number of new coronavirus cases in a single day were recorded within the last 24 hours. 

Speaking in Geneva, Tedros Adhanom Ghebreyesus said, as of Wednesday, there were 24,363 confirmed cases in China and 191 cases in countries outside of China. 

"Of those[cases outside of China], 31 cases are in people with no travel history to China. But all are close to contacts of a confirmed case of someone from Wuhan," he said. 

Ghebreyesus said some high-income countries have stepped up their reporting efforts since he called them out for not sharing "vital case data" on Tuesday evening. 

"Our greatest concern is about the potential for spread in countries with weaker health systems and who lack the capacity to detect or diagnose the virus," Ghebreyesus added.