Amazon staff in the US received a warning email from the firm for not spending enough time in the office after their attendance was tracked.

Some employees were told they were "not currently meeting our expectation of joining your colleagues in the office at least three days a week."

Amazon is not the first tech giant to depart from flexible working rules ushered in during the pandemic.

Disney has already done so and this week Zoom ordered staff to the office.

Amazon's office attendance mandate for American employees took effect in May and stipulates that they have to "badge in" to the office at least three days a week.

The email, sent this week and seen by the BBC, targeted employees who came into the office fewer than three days a week for five or more of the past eight weeks, or for three or more of the past four weeks.

It appeared to exacerbate existing tensions within the company, as some employees said they had received the email in error.

Some Amazon employees in the US staged a walkout to protest the return-to-office push in June.

They said morale at the company was at an "all-time low" due to a series of "short-sighted decisions" by leaders.

Some workers questioned whether the warnings were a sign of an even more strict attendance requirement to come.

In a response to the concerns, Amazon said the message was sent to those who fell short of the policy despite their building being ready for staff's return.

Amazon also admitted that the warnings may have been sent out by mistake in some cases.

"While we've taken several steps to ensure this email went to the correct recipients, we recognize that there may be instances where we have it wrong," the company said.

During pandemic-related lockdowns, many firms opted for remote work. It remains far more prevalent than it was before Covid, due to the flexibility and autonomy it gives workers.

Some companies are rolling back their policies over fears they might dent productivity, but the majority have adopted hybrid working in some way.

When Amazon sent out a memo to inform employees about the new attendance requirements in May, its boss Andy Jassy said the change would help strengthen communication, career development and corporate culture.