Selena Gomez at the Sundance film festival [Photo/Agencies]

Selena Gomez urges Bieber to undergo anger management

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Selena Gomez partied with a mystery man at the Sundance Film Festival.

The 'Come & Get It' singer - who was recently thought to have reunited with her ex-boyfriend, Justin Bieber - appeared at the festival to promote her new film 'Rudderless', on Monday and attended the Grey Goose party alongside a good looking man described as having shaggy blond hair and wearing a green sweater.

A source told People.com: "She went right up to him really early on in the evening."

Selena was then seen hanging out cosily with the mystery man, and casually placed both hands on his legs several times throughout the evening.

Despite their apparent closeness, a representative for Selena claims they are just friends.

The singer and actress later performed two songs at the party before leaving around 1am.

Selena, 21, split from Justin, 19, a second time after allegedly branding him a "drug addict" and urging him to "go to rehab" following a police raid on his mansion last week, during which drugs were found, said to belong to his friend, Lil Za.

In one message Selena is said to have fumed: "I don't buy that any more. I was honest with you and I gave you a second chance."

Meanwhile, Justin is said to have spent $75,000 in a Miami strip club last night while celebrating another friend, Lil Scrappy's, birthday.