A huge VIP party thrown by phone company BlackBerry in London descended into violence last night after one of the 700 guests ended the night in hospital after being stabbed in the neck.

The event at Bankside Vaults in Southwark was supposed to promote the virtues of the BlackBerry Messenger Service (BBM) to an invite-only list of journalists and celebrities, with hit Brit singer Jesse J used as a lure.

Instead it will be remembered for a fight between two attendees as the singer ended her set that has left one of them in a serious condition in hospital and his accused 25-year old assailant in police custody.

"Our first concern is the well-being of the individual concerned,” the company said in a statement. "We are doing all that we can to assist the police with their inquiries."

Police held hundreds of people attending the event for two hours as they established the course of events and trawled for witnesses.

As well as being a personal tragedy, the event is a PR disaster for BlackBerry that had pencilled the unusually large party as a mark of confidence in its troubled platform after weeks of bad news.

Other notables paid to attend included rappers Chipmunk and Tinchy Stryder, comedian Russell Kane, and most of the cast of TV shows The Only Way Is Essex and Made in Chelsea.

Despite recent and possibly misconstrued reports that BlackBerry is giving up on the consumer market, the company’s handsets still have a large following among the UK’s younger smartphone users.