Donald Trump is expected to sign executive orders that include a temporary ban on most refugees and a suspension of visas for citizens of seven countries with Muslim populations, Reuters has reported - citing several people briefed on the matter.
The US president was expected to order a multi-month ban on allowing refugees into the country except for religious minorities escaping persecution, until more aggressive vetting was in place, the news agency reported.
Several congressional aides and immigration experts, who asked not to be identified, said another order would block visas being issued to anyone from Syria, Iraq, Iran, Libya, Somalia, Sudan and Yemen.
CNN also reported Mr Trump was expected to announce orders including restrictions on refugees and visas for people from countries including those seven.
Reuters' sources said the first of the next series of orders would be signed on Wednesday local time (Thursday NZT). But Mr Trump was also considering measures to tighten border security and could turn his attention to the refugee issue later this week, the agency said.
The border security measures could include directing the construction of a border wall with Mexico and other actions to reduce the number of illegal immigrants living inside the US.
This afternoon, on Twitter, Mr Trump said tomorrow would be a "big day" for national security. "Among many other things, we will build the wall," he said.
Stephen Legomsky, who was chief counsel at US Citizenship and Immigration Services in the Obama administration, said the president had the authority to limit refugee admissions and the issuance of visas to specific countries if the administration determined it was in the public's interest.
From a legal standpoint, it would be exactly within his legal rights, Professor Legomsky, a professor at Washington University School of Law in St Louis, said.
But from a policy standpoint, it would be terrible idea because there was such an urgent humanitarian need right now for refugees, he said.
The Republican president, who took office last Friday (Saturday NZT), was expected to sign the first of the orders at the Department of Homeland Security, whose responsibilities include immigration and border security.
On the campaign trail, Mr Trump initially proposed a temporary ban on Muslims entering the US, which he said would protect Americans from jihadist attacks.
Both Mr Trump and his nominee for attorney general, US Senator Jeff Sessions, have since said they would focus the restrictions on countries whose migrants could pose a threat, rather than placing a ban on people who follow a specific religion.
Many Trump supporters decried former President Barack Obama's decision to increase the number of Syrian refugees admitted to the US over fears that those fleeing the country's civil war would carry out attacks.
Legal challenges possible
Detractors could launch legal challenges to the moves if all the countries subject to the ban are Muslim-majority nations, immigration expert Hiroshi Motomura at UCLA School of Law said. Legal arguments could claim the executive orders discriminate against a particular religion, which would be unconstitutional, he said.
"His comments during the campaign and a number of people on his team focused very much on religion as the target," Mr Motomura said.
To block entry from the designated countries, Mr Trump is likely to instruct the State Department to stop issuing visas to people from those nations, according to sources familiar with the visa process.
He could also instruct US Customs and Border Protection to stop any current visa holders from those countries from entering the US.
White House spokesman Sean Spicer said earlier today that the State and Homeland Security Departments would work on the vetting process once Mr Trump's nominee to head the State Department, Rex Tillerson, is installed.
Other measures may include directing all agencies to finish work on a biometric identification system for non-citizens entering and exiting the US and a crackdown on immigrants fraudulently receiving government benefits, according to the congressional aides and immigration experts.
To restrict illegal immigration, Mr Trump has promised to build a wall on the US-Mexico border and to deport illegal migrants living inside the US.
- Reuters / RNZ