The two singers enjoyed spending time with one another at the Coachella music festival in Los Angeles last weekend and decided to see each other again in New York a few days later. A source close to Usher said the pair have been friendly for a long time and have shared some "passionate kisses".
They told The Sun newspaper: "They had a really good time together last weekend and wanted to see each other again somewhere private straight after. They`ve known each other for a long time but it`s always been bad timing.
"They`ve had a few long, passionate kisses. There`s definitely a spark between them. "It would have been too obvious to go somewhere in LA and they were both going back to New York for work commitments."
Earlier this year the `OMG` hitmaker declared his musical interest in the `S&M` star, revealing he wanted to record a duet with her.
He said: "Of course I`d do a track with her - hold on! We`ve been friends and our teams work together and we`ve talked about working together in the past, but it could potentially happen. "I would love to work with her - I think she`s an incredible artist."