Drama is now unfolding behind-the-scenes over the making of Kevin Costner’s Western passion project Horizon: An American Saga.

The Hollywood Reporter claims New Line Cinema has filed an arbitration claim against Horizon Series, the company which produced the films, for alleged breaches to their cofinancing agreement.

The claim was filed after City National Bank moved forward with arbitration proceedings against both New Line and Horizon Series. New Line then filed a cross complaint against Horizon Series for repayment, as part of their defense efforts against the bank.

The deal at dispute is said to have seen both New Line and Horizon agree to repay a share of the film’s financing.

New Line essentially covered what Horizon Series did not pay, however City National Bank believes it is owed more, according to THR.

The amount of money being fought over remains unknown, however Costner, 70, has previously admitted to putting $38 million of his own funds into the two-part epic, which cost more than $100 million to pull together.

DailyMail.com has contacted Costner for comment. New Line had no comment when asked by DailyMail.com and City National Bank also was unable to comment on pending litigation when reached out by DailyMail.com.

New Line declined comment for THR and City National Bank and Territory Pictures did not respond to comment requests from the outlet as well.

A passion project of Costner’s, the two-part Western film series (that is intended to be told over the course of four chapters) starred and was directed by Costner.

Horizon: Chapter 1 was released last June and was slammed by critics and flopped at the box office. A part two, Horizon: An American Saga – Chapter 2, was set to be released in theaters on July 2024 however it was pulled from cinemas and its release is now indefinitely delayed.

In September, Deadline reported parts three and four have scripts and are in a film-ready state.

Costner financed the Horizon films himself, admitting to putting $38 million of his own funds into the project after spending decades trying to find a studio to make the film.

He even took out a loan against his Santa Barbara home after trying unsuccessfully to make it for more than 30 years.

Costner previously told Empire he has taken a gamble by releasing the saga in cinemas.

He said: ‘I had somebody who said, ‘Look, please don’t do this, Kevin, let’s do this.’

‘But I’m glad about what I’m doing. I believe in the big screen. I believe in that experience. I also believe in what will come to your television. You know, I’m not one of those guys that has a director’s cut. The f****** movie I make is the director’s cut.’

The Dances with Wolves star – who is worth an estimated $250million – said: ‘I’m not a fool, but I’m not afraid.

‘I will own this movie the rest of my life. So will my family. And movies are a lot more than their opening weekend. They have value throughout their life, and I will own this movie throughout my life.

‘And people will find it. And when they do, whether it’s opening weekend or not, they’re going to find a quality. They’re going to find a story that they’re going to want to revisit or share with someone. And that’s the power of a movie to me.’

‘My hope is that I get this money back, but you know what, I’m not going to fall apart if it (doesn’t happen).

‘I’ll lose some things that I had valued, but they’re just things I’ve kept. I should add, I don’t want to have to ever do this again. But I don’t live my life in fear.’

The film was released after Costner officially exited his acclaimed Yellowstone series amid a rift with showrunner Taylor Sheridan.