Donald Trump will keep his vow to deport millions of undocumented immigrants from the United States, he said in an interview to be broadcast on Sunday, saying as many as three million could be removed after he takes office.

“What we are going to do is get the people that are criminal and have criminal records, gang members, drug dealers, where a lot of these people, probably two million, it could be even three million — we are getting them out of our country or we are going to incarcerate,” Trump said in an excerpt released ahead of broadcast by CBS's 60 Minutes programme.

The billionaire real estate baron made security at the US-Mexico border a central plank of his insurgent presidential campaign, which resulted in last Tuesday's election victory against his Democratic rival Hillary Clinton.

Trump added that the barrier to be erected on the US border with Mexico may not consist entirely of brick and mortar, but that fencing could be used in some areas.

“There could be some fencing,” Trump says in his first primetime interview since being elected president last week.

“But (for) certain areas, a wall is more appropriate. I'm very good at this, it's called construction,” he tells CBS.

The President-elect had earlier said he would triple the number of immigration and customs enforcement agents and create a “new special deportation task force” to track the most serious security threats.

“The police and law enforcement — they know who these people are. They live with these people. They get mocked by these people,” he said. “They can’t do anything about these people, and they want to. They know who these people are. Day one, my first hour in office, those people are gone.”

An estimated 690,000 undocumented immigrants have committed significant crimes that would make them security priorities — felonies or serious misdemeanours — according to a study by the Migration Policy Institute.

That number is closer to two million according to some, including Jessica Vaughan of the Center for Immigration Studies, whom the Trump campaign has consulted on the issue.