The new coronavirus outbreak can now be characterised as a pandemic, the head of the World Health Organization said Wednesday.

"COVID-19 can be characterised as a pandemic," WHO chief Tedros Adhanom Ghebreyesus told reporters in Geneva. 

The spread and severity of the virus, which has infected more than 110,000 people and killed more than 4,000, is "alarming", Ghebreyesus added.

"We're deeply concerned both by the alarming levels of spread and severity and by the alarming levels of inaction."