Leaked recordings have exposed how Donald Trump’s older sister appears to really feel about her brother’s performance as president.

“He has no principles. None. None,” Maryanne Trump Barry said during 15 hours worth of secretly recorded audio by her niece, Mary Trump.

In one scathing excerpt of a conversation in 2018, Ms Barry is heard accusing her brother of making political moves to “appeal to his base”.

Her comments came after an interview Mr Trump did with Fox News in which he suggested he would put her on the border to oversee cases of immigrant children separated from their parents.

Ms Barry, who was a federal judge at the time, told her niece “I mean my God, if you were a religious person, you want to help people. Not do this”, referring to Mr Trump allowing troops to use force at the US border.

In the recorded phone call, she said “all he wants to do is appeal to his base”.

When talking with her aunt about “what they’re doing with kids at the border”, she said she guesses her brother has never read her opinions on immigration cases.

“What has he read?” Mary Trump asks her aunt.

Ms Barry responds: “No. He doesn’t read.”

President Donald Trump’s older sister, Maryanne Trump Barry, was secretly recorded by their niece. Photo: Getty

She described her brother as “cruel”, saying “it’s the phoniness of it all. It’s the phoniness and this cruelty”.

At another point she says: “His goddamned tweet and lying, oh my God.”

She adds: “I’m talking too freely but you know. The change of stories. The lack of preparation. The lying. Holy shit.”

Mr Trump was dismissive of the recordings which came to light just a day after the late Robert Trump, brother to Ms Barry and the president, was memorialised in a service at the White House.

“Every day it’s something else, who cares. I miss my brother and I’ll continue to work hard for the American people,” Mr Trump said in a statement.

“Not everyone agrees but the results are obvious. Our country will soon be stronger than ever before.”

White House chief of staff Mark Meadows said it was “really a sad day” when a family member secretly tapes 15 hours of a conversation with somebody, “obviously to promote an agenda”.

Mr Meadows said he had not met Ms Barry but had hoped to see her at her brother’s funeral, where he said the president’s tribute showed his compassion and love for his family.

And Mr Meadows, speaking on Fox News, dismissed the idea the president was not well prepared, claiming Mr Trump “reads so much that it causes me to have to read many times well into the night to catch up with him”.

In this 1990 photo, Donald Trump is seen with his mother, Mary; father, Fred; and sister, US District Court Judge Maryanne Trump Barry, right. Photo: AAP

Mary Trump had admitted she made the recordings in 2018 and 2019.

They were first reported by The Washington Post. The Associated Press then obtained the recordings by Mary Trump who recently released a tell-all book denouncing the president.

Titled Too Much and Never Enough: How My Family Created the World’s Most Dangerous Man, the book has come into question in the weeks since its release.

Mary Trump has been questioned about the source of some of its information.

Nowhere in the book does she say she recorded conversations with her aunt. On Saturday, Mary Trump revealed she had covertly taped 15 hours of face-to-face conversations with Ms Barry.

The president has frequently spoken highly of his sister; the recordings are the first time a family member, outside of Mary Trump, has been critical of him.

-with AAP