San Francisco, Mar 12 (IANS): Following the WHO epidemic call over new coronavirus, Seattle and San Francisco on Wednesday banned all large gatherings.

Washington state Governor Jay Inslee said he is banning gatherings of more than 250 people in several counties to try to curb the spread of the new coronavirus, reports CNBC.

San Francisco health officials also announced they were prohibiting public and private events of 1,000 or more.

Washington state is the hardest-hit state in the US with more than 267 confirmed cases.

"The number of cases doubles every several days and we've had multiple instances of COVID-19 in long-term care facilities where vulnerable persons reside. We expect a large-scale outbreak in weeks and this will be a very difficult time," King County health officer Dr Jeff Duchin was quoted as saying.

The ban in Washington state could be expanded to other counties and will likely be extended beyond March.

Moments later, San Francisco Mayor London Breed said: "We know that this order is disruptive, but it is an important step to support public health".

The coronavirus outbreak was Wednesday declared a pandemic by the World Health Organisation (WHO), whose chief expressed his "deep concern" over "alarming levels of inaction" in combating the virus spread.

WHO chief Dr Tedros Adhanom Ghebreyesus said the number of cases outside China had increased 13-fold over the past two weeks, killing over 4,000 and infecting more than 1 lakh people.