WASHINGTON—President Donald Trump is expected to ban entry to the U.S. of people from countries that pose a national-security threat, one of several immigration-related executive actions that will come as soon as Wednesday, congressional officials said.

It is unclear which countries would be included in such a ban.

During the presidential campaign, Mr. Trump initially said he would ban entry by Muslims but later modified his proposal to suspend visas to people from any place “where adequate screening cannot occur.”

Nations to be included in the ban are expected to be principally in the Muslim world. One official said that Mr. Trump also would suspend acceptance into the U.S. of refugees or certain refugees.

He said the president also planned to sign orders related to the issuance of green cards. Another order would relate to tracking people who enter the country legally to be sure that they leave when their visas expire.

White House officials could not be reached for comment.

Mr. Trump isn't expected to act on one of his most controversial promises related to immigration—that he would end a program that helps young people brought to the U.S. illegally as children.

During his presidential campaign, Mr. Trump said he would “immediately terminate” the Deferred Action for Childhood Arrivals program.

But this week, the White House signaled that move wasn't coming soon.

“His priority is first and foremost focused on people who pose a threat to people in our country, to criminals, frankly,” press secretary Sean Spicer said Tuesday. “And that’s where he wants ICE [the Immigration and Customs Enforcement agency] to focus their efforts.”