Justin Bieber may have vowed to his fans to focus on music and remain positive but the controversies don't seem to leave the singer's side soon as more details have emerged over what caused the bloody nightclub brawl at the wee hours on Sunday.

According to a witness, the brawl at the South Pointe nightclub in Southampton started over an attractive waitress and a bow tie!

A witness told the New York Post that as the 19-year-old singer left the club with two waitresses, the guys on the next table did not appear happy as "one of the waitresses - a very attractive blonde - was flirtatiously wearing a bow tie, which one of the guys on the next table had loaned to her."

"As she got into Bieber's SUV, the guys chased her out, saying they wanted the bow tie back. Bieber's security pushed back, and a scuffle started," the witness said adding that as the singer and his security guards drove away "someone threw a rock at his car. Bieber jumped out of the sun roof and got on the hood of the car, while his security knocked the guy to the floor."

Police were called by the alleged victim, who was hospitalised Saturday night at Peconic Bay Medical Center but has now been released. Cops have interviewed the club's owner, security and staff. It is believed some of the action was caught on security cameras which has a footage of the "Baby Baby" hitmaker does not make any physical contact with the victim but is seen leaping out of an SUV's sunroof as his security guards are allegedly beating the man.

Justin's security team is now reportedly under police investigation for assault. However the spokespersons for the night club and the singer have both denied any altercation took place.

"There was no incident in the club or on the premises," Melanie Weitzner said.

"Justin wasn't involved in the altercation," his representative said.

Amid all that happened Bieber appeared calm and brushed the incident as "rumors." "The most recent rumors might be the funniest of all. Where do u get this stuff??? #focusedonreality," he tweeted.

The New York post also reports that the singer is partying at "a private ocean front property" with the two waitresses and the club's DJ.

This is not the first time that singer got involved in controversial situation. Earlier in March, Bieber was involved in an altercation with a photographer in London which resulted in him being restrained by his own bodyguard. Bieber swore at the photographer, threatening to "fucking beat the fuck" out of him.