Justin Bieber fuels Kourtney Kardashian 'hook up' claims as he appears to mock Scott Disick on Instagram

·         BY REBECCA MERRIMAN

Insiders have revealed the unlikely duo are having 'fun' together, but what about Kourtney's on-off partner of nine years?

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Are Justin and Kourtney really enjoying a romance?

Justin Bieber appeared to hint at his rumoured relationship with Kourtney Kardashian on Sunday in a suggestive Instagram picture.

Standing with his back to the camera a brunette with her face obscured could be seen in a very comprising position with the star, while sitting on the hood of his Ferarri.

He captioned the picture "Lord knows," in what could be seen as a dig at Scott Disick- Kourtney's long time boyfriend - who is known as Lord Disick.

https://www.instagram.com/p/_QNy7bAvk6

It comes following reports the Keeping Up With The Kardashians beauty, who was spotted out with the 21-year-old star on Friday night, has been "casually hooking up" with the Sorry singer.

Justin and Kourtney are said to have hit Hollywood hot spot the Nice Guy, before hitting the Blind Dragon karaoke club. Gossip Cop claimed she was later photographed leaving the Montage Beverly Hills hotel at around 4am - a hotel Justin frequently stays at.

Kourtney Kardashian and Justin Bieber leaving 'The Nice Guy' together in October

Insiders stressed it isn't a serious relationship between the couple - who were also spotted out together in October - saying "it's just fun."

Neither Kourtney - who was believed to be getting back with ex-boyfriend Scott Disick - or Justin have responded to the claims.

Kourtney, who is 15 years older than her rumoured beau, was on mum duty on Sunday as her sons Reign and Mason celebrated their first and sixth birthdays.