WENN

Former couple Khloe Kardashian and Tristan Thompson have threatened a woman who alleged he is the father of her child with legal action.

The reality TV star and her sportsman ex, who share a two-year-old daughther, True, hit the headlines again this week as she has denied she is pregnant with their second child.

U.S. tabloid website Gossip of the City also published copies of paperwork purportedly from DNA testing service LB Genetics suggesting Tristan took a paternity test in January and Khloe and Tristan have now sent a cease and desist letter to the woman concerned, Kimberly Alexander, according to E! News.

In the letter sent by the ex-couple's attorney, Marty Singer, on Wednesday, they ask Kimberly to "immediately stop defaming them with malicious defamatory lies and specious fabrications" regarding the paternity claim.

Gossip of the City's report featured screenshots of text messages allegedly sent by Tristan to Kimberly, as well as emails she apparently received from her former attorney, Lisa Bloom.

In the legal letter, Marty confirms that Tristan did take a paternity test, but that it was negative, and that he agreed to take a second test on the condition it was carried out by an AABB-accredited laboratory.

"After it was indisputably established by a paternity test performed by one of the most reputable labs that Mr. Thompson is not your child's father, we thought that would be the end of this," the letter reads, accusing her of spreading, "outrageous lies about my clients, including ridiculous fictional conspiracy theories" alleging the negative test was falsified.

The attorney goes on to claim that Kimberly was "fired" by Bloom's legal firm and accuses her of seeking "15 minutes of fame" before threatening her with a "multi-million dollar" lawsuit if she does not comply with the letter's demands.