The coronavirus outbreak has reached a "decisive point" and has "pandemic potential", World Health Organization head Dr Tedros Ghebreyesus says.
His comments come as countries around the world battle to prevent the virus spreading further.
For a second day, more cases have been reported outside than inside China.
Iran and Italy have become major centres of infection, with people travelling from there spreading the virus further afield.
Several high-profile Iranian officials have become infected, the latest being Vice-President for Women and Family Affairs Masoumeh Ebtekar.
"It's what's happening in the rest of the world that's now our greatest concern," Dr Tedros said.
Globally, more than 80,000 people in nearly 50 countries have been infected. Nearly 2,800 have died, the majority in China's Hubei province.
Meanwhile stock markets around the world have fallen sharply amid fears that increased travel restrictions will prevent business activity.
(Source: BBC News)