A man is in hospital in a critical condition after he was stabbed in the neck with a glass bottle at a party - hosted by the firm which makes Blackbery smartphones - in the Pulse nightclub near Blackfriars Bridge.
The party at Pulse (also known as Bankside Vaults) was held to promote the BBM service. Guests included footballers, reality TV stars and journalists as well as winners of competitions organised by Research in Motion, the makers of Blackberry products.
It is believed that the man was injured soon after the headline act, Jessie J, came off stage.
A police spokesman said that the man – thought to be in his thirties – suffered a neck injury which appeared to have been inflicted by a bottle.
He was taken by ambulance to an east London hospital where, as of Wednesday lunchtime, his condition is understood to be critical.
A 25-year-old man was arrested on suspicion of assault and is now in custody at a south London police station.