Donald Trump once made a pact with his daughter Ivanka never to date anyone younger than her.

In a recently unearthed interview on The Howard Stern Show in 1999, Trump joked about how he was attending fashion events to meet a model to be his next wife.

When he was asked how that affects his daughter, Trump responded: 'I have a deal with her. She's just 17 and she's doing great, Ivanka, and she made me promise her - to swear to her - that I would never date a girl younger than her.'

He continued: 'So as she grows older, the field is getting very limited.'

In 1999, Donald Trump told Howard Stern that he made a pact with his then 17-year-old daughter not to date anyone younger than her. The father and daughter pictured on the left in 1997 and on the right in 1993

Stern responded: 'Yeah, I mean the nerve of her, now you can't go out with 16 year olds.'

At the time of the interview, Trump had already started dating his future wife number three, Melania, who is actually closer in age to Ivanka. Trump is 70 years old while his wife and eldest daughter are 46 and 34 respectively.

The interview was unearthed by a Democratic strategist who shared it with the New York Daily News.

At the time of the Howard Stern interview, Trump had already begun dating his future wife Melania (pictured above at Monday night's debate), who is actually closer in age to his daughter

The interview just adds to plethora of uncomfortable comments the Republican nominee has made about his eldest daughter.

In another Howard Stern interview from 2003, Trump bragged about his daughter's figure, saying: 'You know who’s one of the great beauties of the world, according to everybody? And I helped create her. Ivanka. My daughter, Ivanka. She’s 6 feet tall, she’s got the best body. She made a lot money as a model—a tremendous amount.'

He's also suggested that he might be dating his daughter, if they weren't related.