Microsoft CEO Satya Nadella has sharply criticized US President Donald Trump’s "zero tolerance" immigration policy.

In a letter to employees, Nadella said, "I am appalled at the abhorrent policy of separating immigrant children from their families at the southern border of the US. As both a parent and an immigrant, this issue touches me personally."

The 50-year old company veteran clarified that Microsoft is not directly working with Immigration and Customs Enforcement (ICE) or US Customs and Border Protection on these immigration policies that is "separating children from their families at the border."

"Our current cloud engagement with US ICE is supporting legacy mail, calendar, messaging and document management workloads," he said.

India-born Nadella also highlighted the importance of immigrants and their ubiquity in Silicon Valley. In 2009, the New York Times reported that half of all Silicon Valley engineers were born overseas.

"America is a nation of immigrants, and we’re able to attract people from around the world to contribute to our economy, our communities and our companies," said Nadella."This is what makes America stronger. We will always stand for immigration policies that preserve every person’s dignity and human rights."

His comments come after the White House announced the policy of separating undocumented child immigrants from their parents and housing them in detention centres.

Trump is facing growing criticism from supporters and opposition Democrats over the hardline push by his administration.