Reality TV star Khloe Kardashian's family have reportedly warned her to dump her beau, rapper French Montana.

The Kardashians, including Khloe's sister Kim Kardashian West and mother Kris Jenner, believe Montana has been unfaithful to Khloe and think he even used Kim as a cover for his infidelity, reports tmz.com.

During a recent trip to Dubai, Montana is believed to have been hooking up with a woman in between bumping into Kim long enough to have his picture taken with her in order to trick Khloe into thinking he was simply hanging out with her sister and other pals.

However, the rapper's plan is said to have unravelled when Kim arrived back in America and told Khloe she'd spent very little time with French, leading to the family becoming convinced he used Kim to deceive her own sister.

Meanwhile, Montana recently claimed he would refuse to sign a prenuptial agreement if he were to marry Khloe after it took him two years and $2 million to finalise his divorce from ex-wife Nadeen Kharpouch.