Donald Trump "has no principles" and people "can't trust him" according to his eldest sister, the first rebuke of the president from any of his siblings to be made public since he took office.

In secretly recorded audio published by the Washington Post on Saturday, Maryanne Trump Barry, a retired federal judge, talks candidly to the president's niece, Mary Trump, about her relationship with her brother, apparently unaware that she is being recorded.

The president's niece has held longstanding animosity toward her uncle and recently released a tell-all book claiming the president cheated on his college entrance exams, among other revelations. The recordings' release comes as many members of the Trump family are scheduled to speak at the Republican National Convention next week.

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