Google's parent company Alphabet has asked its North American staff to work from home to reduce the potential spread of the coronavirus.

Last week the tech giant sent a memo to staff recommending that employees in Washington state work from home.

It has now expanded that request to all of its almost 100,000 workers across 11 office in the US and Canada.

Alphabet is the latest company to make such an announcement as US coronavirus cases have risen to almost 1,000.

"Out of an abundance of caution, and for the protection of Alphabet and the broader community, we now recommend you work from home if your role allows," Chris Rackow, Google's vice president of global security, wrote in an email to workers.

Alphabet said its offices in North America will remain open for those whose jobs require them to come in.

Last week, Google, along with many of the world's other major tech companies, including Apple, Amazon, Microsoft and Facebook, began recommending that staff in Seattle should work from home as the coronavirus spreads in Washington state.

The state had more than 160 cases as of Monday night. California and New York, where Alphabet has large offices, are also experiencing spikes in the number of cases.

An employee at Amazon and an employee at Facebook have been diagnosed with the coronavirus.

On Sunday, Apple chief executive Tim Cook asked employees at several of its global offices to work remotely this week "if your job allows".

Last week Twitter told its employees to work from home to help stop the spread of the virus. In a blog post, the social media giant said it was mandatory for staff in Hong Kong, Japan and South Korea to work remotely.

Twitter also said it was "strongly encouraging" all of its 5,000 employees around the world to not to go into their offices.