Kim Kardashian West and Kourtney Kardashian. Picture: Instagram

Kim Kardashian West slammed her sisters Kourtney and Khloe for their "disgusting" fashion choices on a trip to Japan.

The 37-year-old star took a trip to Japan to shoot a campaign for husband Kanye West's Yeezy label and took along her siblings Kourtney and Khloe Kardashian, but wasn't impressed by their choice of outfits, branding them "f***ing clowns" who needed to overhaul their images to stay "young and relevant".

Speaking on the latest episode of 'Keeping Up With the Kardashians', she said: "I can't even eat dinner because I'm so disgusted with my sisters' crazy outfits that completely don't go with my look. Like, I can't take it.

"My sisters' look so crazy. It's actually embarrassing. Kourtney with the Japanese-inspired outfit and Khloe is wearing silver sequins, turquoise eyeshadow, huge chandelier earrings -- they're just like, completely clashing and making my outfit look really bad and they're ruining everything. 

"I need the Yeezy collection to be debuted and not all this crazy distraction in the background."

She then fumed to the pair: "So I gotta be real with you guys. You look like f***ing clowns. I'm not kidding. 

"This is not like, a tourist thing where it's Halloween, dress up like a f***ing Japanese geisha, unless we're at a geisha house. I just think you've got to like, chill. Like, you can be cooler. 

"I'm not telling you guys who to be and what to wear or anything, but I'm telling you who to be and what to wear. It could be time for a fashion overhaul so that you stay young and relevant."

And Kim - who has children North, five, Saint, two, and Chicago, eight months, with Kanye - later lashed out at Kourtney, 39, again for looking like a "grandma".

She told her older sister: "You look like f***ing grandma. 100%. You don't look anything special. Like you don't look anything innovative. And I think you have it in you, it's just you better evolve before you fizzle out."

While Kim admitted she had been "snappy and very opinionated", she claimed her unkind comments came because she was busy focusing on the Yeezy campaign.

Kourtney replied: "But I feel like we're also here to have fun, wear some fun stuff, do some fun makeup, whatever. And by the way, I liked all my outfits.

"Nobody wants to wake up and be criticised from head-to-toe the whole day long."

Shocked Kim pointed out the "old Kourtney" would have fought back against her comments, but the mother-of-three said: "So would you rather me f***ing say your f***ing outfits suck? You're wearing a puffy vest, you have pink hair and turquoise shoes.

"I didn't come here to wear leggings that are see-through and show my ass off. 

"Do you know easy it is to a b***h? I could be a b***h all f***ing day if that's what you want. But guess what? It takes a lot more courage to show your feelings than to sit there and be a b***h."

Kim eventually promised to "work on" the way she gets her message across to people.

She reflected: "I feel like I always