SEATTLE, United States — Amazon.com Inc on Tuesday told employees whose work can be done from home that they can do so until June, extending the timeline on a return to office due to the Covid-19 pandemic.

"Employees who work in a role that can effectively be done from home are welcome to do so until June 30, 2021", an Amazon spokeswoman said in an emailed statement on Tuesday, adding the guidance is applicable globally.

Amazon had earlier allowed that option until January.

The development comes less than three weeks after the world's largest online retailer said more than 19,000 of its US frontline workers contracted the coronavirus this year.

Some staff, elected officials and unions in recent months have said that Amazon put employees' health at risk by keeping warehouses open during the pandemic.

"We have invested significant funds and resources to keep those who choose to come to the office safe through physical distancing, deep cleaning, temperature checks, and by providing face coverings and hand sanitiser," the Amazon spokeswoman said on Tuesday.

In May, Twitter Inc became the first major tech company to allow employees who can work remotely to do so indefinitely.

Other tech giants have extended the work from home option for their employees with Microsoft Corp saying earlier this month it will let most employees work remotely for up to half their weekly working hours.

Facebook Inc had said it would allow its employees to work from home till July next year, while Google had extended the remote working period for employees who do not need to be in the office till June.

By Kanishka Singh; editor: Amy Caren Daniel.