President Donald Trump says he's planning to sign an executive order to end what he called the "ridiculous" practice of granting citizenship to children born in the US to noncitizen parents.

The 14th Amendment to the US Constitution, ratified by Congress in 1868 as part of the civil-rights amendments after the Civil War, says all people born in the US are citizens.

With the order, Trump's lawyers would most likely argue that the amendment doesn't apply to children of unauthorized immigrants.

President Donald Trump plans to sign an executive order meant to end what he called the "ridiculous" practice of extending citizenship to children born in the US to noncitizen parents.

"It was always told to me that you needed a constitutional amendment" to end the practice called birthright citizenship, Trump told Jonathan Swan of the news website Axios on Monday. "Guess what? You don't."

"You can definitely do it with an act of Congress," Trump added. "But now they're saying I can do it just with an executive order."

Read more: Trump plans to end birthright citizenship — here's what the law says about that

The 14th Amendment to the US Constitution, ratified by Congress in 1868 as part of the civil-rights amendments after the Civil War, says, "All persons born or naturalized in the United States and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside."

In a video of the interview published by Axios, Trump did not elaborate on the legal arguments an executive order would include. The proposal, which is sure to face challenges in court, would probably seek to deny citizenship only to children born in the US to unauthorized immigrant parents. Trump's lawyers would most likely argue that the amendment applies only to children of lawful US residents and not unauthorized immigrants or those on temporary visas.

"How ridiculous, 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 said. "It's ridiculous. It's ridiculous and it has to end."

As Axios pointed out, more than 30 countries provide birthright citizenship, most of them in the Western Hemisphere.

"It's in the process," Trump said. "It will happen with an executive order."