Nich Lachey is reportedly dating his ex-wife's best friend and assistant.

Life & Style magazine claims that Lachey and Cacee Cobb were spotted kissing and cuddling at LA nightclub Level 3 last week.

According to one partygoer, "Nick had his arms wrapped around her, and he was kissing her all over the side of her face and neck. Her arms were around him, too. We were watching in total disbelief. We kept waiting for them to rip each other's clothes off."

"There may be nothing going on between them," added another onlooker, "but it was inappropriate behaviour. Everyone was like, "Wow, what are they thinking?"

However, Lachey's representatives have rubbished the rumours, stating: "Nick and Cacee are friends. That's it."