A Google spokesperson said the company made the decision after consulting with public health officials.

Seattle-headquartered Amazon recommended that employees in the area work from home through the end of the month, after an employee at its South Lake Union office complex in the city tested positive for the coronavirus on Tuesday.

Facebook on Thursday said it would shut its Seattle office until March 9 after a contractor at the location was also diagnosed.

The companies' work-from-home recommendation will affect more than 100,000 people in the Seattle area, as both Microsoft and Amazon employ over 50,000 workers each. Facebook employs more than 5,000 in the area, and Google about 4,500, according to media reports.

Seattle health authorities have urged companies to allow their employees to work from home as much as possible, stagger shifts to ease commuter congestion on public transportation, and avoid large work-related gatherings.

The epidemic has shown no signs of slowing, and so far killed more than 3,000 people worldwide, mostly in China, where it originated in December.

Separately, retailer Walmart Inc said on Thursday it was restricting all international travels to business-critical trips, and travels within the US to essential operations for its associates.

It also cancelled its Walmart US Customer Conference, scheduled for the following week in Dallas. The company said it expected travel guidelines to be in place for at least the months of March and April.

Big tech companies have also been dropping out of several conferences and calling off corporate events as the virus spreads.

The epidemic has led to the cancellation of major industry events, including the Mobile World Congress in Barcelona and Facebook's F8 conference in San Jose, California.

Microsoft said on Wednesday that some "essential" employees should continue to go to their work locations and that the company would follow government guidelines for disinfecting its sites for essential personnel.