San Francisco: America is a nation of immigrants and should be proud of it, Facebook CEO Mark Zuckerberg said on Saturday as he criticised President Donald Trump's decision to severely limit immigrants and refugees from certain Muslim-majority countries.

"Like many of you, I’m concerned about the impact of the recent executive orders signed by President Trump," Zuckerberg wrote on his Facebook page.

"We need to keep this country safe, but we should do that by focusing on people who actually pose a threat. We should also keep our doors open to refugees and those who need help. That’s who we are."

"We should also keep our doors open to refugees and those who need help. That's who we are. Had we turned away refugees a few decades ago, Priscilla's family wouldn't be here today," he wrote of his wife, Priscilla Chan, whose family were refugees from China and Vietnam.

"These issues are personal for me even beyond my family. A few years ago, I taught a class at a local middle school where some of my best students were undocumented. They are our future too. We are a nation of immigrants, and we all benefit when the best and brightest from around the world can live, work and contribute here. I hope we find the courage and compassion to bring people together and make this world a better place for everyone," he said.

(Photo: Facebook)

Trump signed an executive order Friday that puts a moratorium on allowing refugees from a list of predominantly Muslim countries to enter the United States.

Zuckerberg, who has long championed immigration, wrote that his great grandparents came from Germany Austria and Poland.

While keeping America safe is important, he said that the way to do it is to focus on those who actually pose a threat.

"Expanding the focus of law enforcement beyond people who are real threats would make all Americans less safe by diverting resources, while millions of undocumented folks who don't pose a threat will live in fear of deportation," he said.

Zuckerberg also prodded Trump to stand by earlier statements regarding Deferred Action for Childhood Arrivals (Daca) and H1-B visas, which are of particular concern to tech companies that use the visas to hire talent from overseas.

Zuckerberg’s statement, though restrained, is notable at a time when the rest of Silicon Valley appears to be rushing to fall in line with the Trump administration.

Tech leaders had overwhelmingly opposed Trump's candidacy during the campaign. But following Trump's surprise election, tech leaders quickly changed their tune.