Mark Zuckerberg 'concerned' by Donald Trump's refugee cuts

Facebook founder Mark Zuckerberg has lashed out at US president Donald Trump's crackdown on refugees and immigrants.

In a lengthy post on his own Facebook page, the billionaire CEO noted his wife Priscilla's parents were refugees from China and Vietnam, and his own great-grandparents immigrated to the US from Germany, Austria and Poland.

"The United States is a nation of immigrants, and we should be proud of that," he wrote. "Like many of you, I'm concerned about the impact of the recent executive orders signed by President Trump."

Mr Trump has only been the US president for a week, but has already signed a number of executive orders changing US policy. He signed two on Friday (local time) alone - one boosting US military spending and the other tightening the country's borders with "new vetting measures to keep radical Islamic terrorists out".

The US will also cut the number of refugees it accepts annually by half, blocking those fleeing wars in Iraq, Syria, Iran, Sudan, Libya, Somalia or Yemen.

"We need to keep this country safe, but we should do that by focusing on people who actually pose a threat," Mr Zuckerberg writes.

"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.

"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."

Women's rights activist Malala Yousafzai, the youngest person to ever win the Nobel Peace Prize, also expressed dismay at Mr Trump's decision.

"I am heartbroken that today President Trump is closing the door on children, mothers and fathers fleeing violence and war," she wrote on Facebook.

"In this time of uncertainty and unrest around the world, I ask President Trump not to turn his back on the world's most defenseless children and families."

Christians first, says Trump

Mr Trump has been open about his reasons for blocking refugees from Muslim countries, many of whom have been wracked by fighting involving the US - he'd rather let Christians in.

"Do you know if you were a Christian in Syria it was impossible, at least very tough, to get into the United States?" he told the Christian Broadcast Network on Friday.

"If you were a Muslim you could come in, but if you were a Christian, it was almost impossible and the reason that was so unfair, everybody was persecuted in all fairness, but they were chopping off the heads of everybody but more so the Christians. And I thought it was very, very unfair."

Mr Trump did not provide any evidence US agencies were prioritising Muslims over Christians, CNN reports.

The American Civil Liberties Union called Mr Trump's order "just a euphemism for discrimination against Muslims".