Kevin Costner was at odds with the British royal family in the 1990s.

During his interview on “The Howard Stern Show” on Tuesday, the Oscar winner, 69, confirmed that a sequel to his hit 1992 film “The Bodyguard” with Whitney Houston was in the works with Princess Diana as his planned co-star.

However, Diana’s death in summer 1997 caused the project to be canceled — and Costner subsequently faced the wrath of the royals, who didn’t believe that the princess was willing to do a Hollywood movie.

Princess Diana and Queen Elizabeth.Tim Graham Photo Library via Getty Images
“When Diana passed, about a year later it had leaked out that I was prepping ‘Bodyguard 2’ with her. And what happened was, the royal family kind of turned on me a little bit,” he recalled.

“Like, ‘No, that’s not true.’ And it got actually kind of ugly,” Costner continued. “And I let it go for a while. It just got uglier and uglier.”

Kevin Costner had plans for another “Bodyguard” film leading up to Diana’s death.Charles Wenzelberg/New York Post

Kevin Costner in “The Bodyguard.”©Warner Bros/Courtesy Everett Collection

The “Yellowstone” star said that he ended up reaching out to Sarah Ferguson, Duchess of York, who initially connected Costner with Diana, and asked for her help.

“Finally I called up Sarah, and said, ‘Sarah, you need to tell me who is leading the charge there on this thing. She goes, ‘No, no, no, Kev, you don’t want to talk to them.’ I said, ‘Yes I do.’ I called them up and I said, ‘I’m telling you something, you need to stop because it is true. And if you don’t stop, I’m gonna start. Because it was.’”

The Post has reached out to Buckingham Palace for comment.

Princess Diana in London in April 1993.Getty Images
At the time that Costner was trying to make “The Bodyguard 2,” Diana was separated from her former husband Prince Charles (now King Charles) and was on the outs with the royal family ruled by the now-late Queen Elizabeth II.

Costner explained how he got Diana to agree to do the film.

“What had happened was, I started talking to her through Sarah, and I said, ‘Look, I’m gonna do ‘Bodyguard 2′ and I think I can build this around you. Would you be interested?’ ” he recalled. “And she goes, ‘Yes. My life’s about to change.’ I didn’t really go into depth with it, but I thought I understood what she was saying.”

Kevin Costner and the late Whitney Houston in “The Bodyguard.”©Warner Bros/Courtesy Everett Collection
He added, “She was very sweet and we talked. The second time we talked she said, ‘Is there going to be a kissing scene?’ I said, ‘Do you want there to be one?’ She said, ‘Yeah,’ and I said, ‘Then we’ll do that.’ I wasn’t going to make the full romance about her. But there was going to be a moment that we did. And she was so sweet about this.”

Diana died in a car crash in Paris in August 1997 at the age of 36, and Costner decided not to move forward with “The Bodyguard” sequel. “I could not replace Princess Di,” he said.

Princess Diana in March 1993, roughly four years before her death.Getty Images
Costner also revealed that years after Diana’s passing, he heard from her eldest son Prince William, who wanted to meet with the actor in Scotland.

“We meet in a room. There’s nobody in the room. I sat across from him and he looked at me and he said, ‘My mom fancied you,” he recalled. “It was the sweetest, gentlest thing. He believed the story, and believe it or not after the talk with the royal family, about two years later the butler came out and said, ‘Yeah, that was the true what Kevin was saying, that she [Diana] was gonna do it.’”

Princess Diana with her sons in March 1993.Getty ImagesCostner first spoke about the plans for “The Bodyguard” in 2012, explaining that the plot was going to explore Diana’s complicated relationship with the paparazzi. He said at the time that a script for the film arrived on his desk the day before Diana’s death.

Ironically, Diana died trying to flee paparazzi, who were chasing her through the streets of Paris that night.