An open letter signed by more than 100 Microsoft employees has called on the tech giant to stop its work with US Border Patrol.
The call comes as the Trump administration faces intense criticism over the separation of children from their families at the Mexican border.
The letter says the employees “refuse to be complicit”.
Microsoft has said its technology was not being used for “projects related to separating children from their families at the border”.
In a statement published before the employee letter surfaced, the company said: “Microsoft is dismayed by the forcible separation of children from their families at the border. Family unification has been a fundamental tenet of American policy and law since the end of World War II.”
However, the firm does have a $19.4m (£14.7m) contract with the US Immigration, Customs and Enforcement agency, known as ICE.
In January, it posted information about how its cloud computing platform, Azure, was being used to facilitate data “security and compliance”.
The post read: “We’re proud to support this work with our mission-critical cloud.”