Cases of Covid-19 have been reported at more than 50 Amazon facilities across the US. Some have involved multiple infected workers.

The company said it had assembled a team to build its own “incremental testing capacity”.

Amazon staff have previously criticised the firm over its response to the coronavirus pandemic.

In March, Amazon fired a New York warehouse worker who organised a protest over a lack of safety precautions taken by the company.

In a statement, Amazon said “We did not terminate Mr Smalls’ employment for organizing a 15-person protest. We terminated his employment for putting the health and safety of others at risk and violations of his terms of his employment. Mr Smalls received multiple warnings for violating social distancing guidelines.”

Later, a memo from a meeting of Amazon executives was leaked. It said: “We should spend the first part of our response strongly laying out the case for why the organiser’s conduct was immoral, unacceptable, arguably illegal, in detail, and only then follow with our usual talking points about worker safety.”