U.S. President Donald Trump said on Wednesday that his administration is seriously considering an executive order to end birthright citizenship.

"We're looking at that very seriously," Trump told reporters when leaving the White House for the U.S. state of Kentucky.

"Birthright citizenship, where you have a baby on our land - walk over the border, have a baby, congratulations, the baby's now a U.S. citizen," said the president. "It's, frankly, ridiculous."

Trump promised ending the birthright citizenship during his 2016 presidential campaign and once revived the idea last year, according to a report of The Hill.

Earlier Wednesday, acting Homeland Security Secretary Kevin McAleenan unveiled new policies which will allow the government to detain families crossing the U.S.-Mexico border longer than before. If the new rule survives court challenges, the policy change could permit authorities to detain families through the duration of their immigration proceedings.

The U.S. federal government has sought various ways to curb illegal and legal immigration since Trump was sworn in in January 2017.