Trump's comments come ahead of the US midterm elections that he has sought to focus on his hardline immigration policies. Photo: Reuters

In an interview with "Axios on HBO", Trump said he is working with legal counsel to put an end to the practice, which has existed since 1968 and stipulates that citizenship is automatically granted to any person born within US territory.

Revoking birthright citizenship would lead to a court fight over whether the president has the unilateral ability to change an amendment to the Constitution. The 14th Amendment guarantees that right for all children born in the US.

Asked about the legality of such an executive order, Trump said, "they're saying I can do it just with an executive order". "It's ridiculous and it has to end ... "

It's unclear how quickly he would act on an executive order.

"We're the only country in the world where a person comes in, has a baby and the baby is essentially a citizen of the United States for 85 years with all of those benefits," Trump told the Axios HBO series, which debuts on Sunday.