The number of confirmed coronavirus-related pneumonia cases caused by a new virus in Central China's Hubei province rose to 549 as of Thursday midnight, including 24 deaths, provincial authorities said on Friday.

In Wuhan, capital of the province and epicenter of the outbreak, 495 cases had been confirmed as of Thursday at midnight, and new cases were confirmed for the first time in four cities in the province, including Xiaogan and Xiantao.

A total of 494 people in Hubei are still receiving treatment under quarantine in hospitals, including 23 in critical condition; 31 people have been cured and released from the hospital.

Authorities in the province traced 3,653 close contacts of the patients and put them under medical observation on Thursday night, with 877 released.