Kourtney Kardashian branded her sister Kim Kardashian a "witch" and told her "I hate you" during an explosive argument.
The siblings' relationship has been rocky in recent months following a number of fall outs and it seemingly took another turn for the worse in an emotional row which has been shown in the teaser for the new season of their family reality show 'The Kardashians'.
In the clip, 42-year-old SKIMS founder Kim is seen telling have a dispute over speakerphone with her sister, saying: "Are you happy? You’re a different person, you hate us … We’re all just talking about it ...
"You think things, so you get riled up. I think things, so I’m getting riled up."
Kourtney, 44, then tells her: "You’re just a witch and I hate you."
During a confessional speech to cameras, Kim later added: "The dynamic is changing. Everyone’s lives are going in different directions," while in a joint session featuring both sisters Kourtney added: "There’s been a lot of tension. It’s really hard to watch people talking about you. I don’t feel understood."
However, the teaser ends on a positive note with younger sister Khloe insisting she's sure the issues between Kourtney and Kim can be resolved. She said: "These things are fixable. It’s not going to break us down."
It comes after Kim and Kourtney were seen falling over during the last season of the reality show in a row over their relationship with Italian fashion house Dolce and Gabbana.
The spat between the sisters played out on camera with Kourtney accusing Kim of copying her by lifting Dolce and Gabbana looks from her wedding to Travis Barker in the Italian town of Portofino last year when she curated a fashion show for the brand months later.
The sniping continued when Kim pointed out Andrea Bocelli sang at the reception when Kourtney married Travis, but he had previously performed when Kim tied the knot with Kanye West in the Italian city of Florence in 2014.
Kourtney previously slammed her sister for agreeing to work with Dolce and Gabbana on a fashion show after the designers collaborated on her wedding dress and looks for her guests over the course of her trip to Italy.
Speaking on the show, Kourtney fumed: "It feels awful that my sister used my wedding as a business opportunity. She chose the money over me - that’s why she never truly asked me [about whether to do the fashion show].
"It’s not that she forgot to ask me or thought that I wouldn’t care. I think she wouldn't have known what to do if my answer was no."
The fourth season of 'The Kardashians' is set to debut on September 28 on Hulu.