Sources claimed that the singers were seen "strolling around hand-in-hand" at this weekend's V Festival and later "started kissing before disappearing from the party together".
Brown fuelled speculation by tweeting that V had been "defo one of the best weekends I've had in a while", but a spokesperson for Jenkins has since told The Sun that the pair were "just being friendly" and "having a fun time".
The Dancing with the Stars contestant has now addressed the claims herself on Twitter, describing them as "simply not true".
"It's really starting to frustrate me that I can't talk to a guy without it being reported that we are now together," she wrote. "And to say I kissed him??
"Your source clearly had one too many of the Mahiki cocktails! This is simply NOT TRUE! #Aaaargh."
She concluded: "Right, got that off my chest... Let's do some work shall we?! Off to a photoshoot. Happy Tues beautiful twitter people!"
Jenkins split with fiancé Gethin Jones in December and has been linked to Dancing with the Stars colleague Derek Hough in recent times.