Kim Kardashian is allegedly "envious" of her sister's X Factor job.

Relations between the 32-year-old Keeping Up With The Kardashians star and her 28-year-old sibling Khloe are reportedly very tense since her younger sister secured the high profile presenting job last month. A source told Life & Style magazine that the reality TV star "has become deeply envious" of Khloe's job and it has already "led to some serious tension" in their family.

"Kim and Khloe has been fighting lately because Kim is extremely jealous of Khloe's career. [Kim] feels like Khloe had become the breakout star of the family, and she hates it," an insider said.

Khloe - who is married to Clippers basketball star Lamar Odom - previously revealed that her older sister had given her constructive criticism on how to improve her presenting skills. "My sisters have already texted me tips, which I love. I love constructive criticism. I've never done this before, so I just think I can only get better - hopefully. My sister Kim was like, 'You did amazing, but don't yell so much!' I did notice at some points, I was like, 'Why did I just yell?'" she explained.