Jessie J
British singer Jessie J

A man has been seriously injured after reportedly being stabbed in the neck at a party attended by singer Jessie J in London.

The victim is believed to have been attacked with a bottle just after midnight inside Pulse underground nightclub in Southwark, central London, where the party was hosted by the smart phone company BlackBerry to promote its instant messaging service.

"A man in his 30's was taken to an east London hospital and is in a serious condition. One man was arrested and is in custody," the Telegraph quoted the police as saying.

Brit-award winning singer Jessie J had earlier performed at the event

The party was attended by several journalists, celebrities including rappers Chipmunk and Wretch 32 and winners of the BlackBerry competition.

Benjamin Cohen, Channel 4's technology correspondent, who was at the event told the Telegraph that he saw a bouncer covered in blood in the toilets.

"Everyone tried to leave at the same time but the organisers weren't geared up for it and there was a huge rush to get to the cloakroom," he said.

"People were crying and quite a lot were being sick, whether from the blood or the alcohol. A lot of people here were teen users of BlackBerry who don't seem to have had a free drink before," he added.

The BBC reported that a spokesman for Blackberry-maker Research in Motion (RIM) said: "Our first concern is the well-being of the individual concerned."

"We are doing all that we can to assist the police with their inquiries."

Singer Jessie J posted a message on her twitter page saying: "My thoughts are with the person who was seriously injured last night at the blackberry bbm party. So sad. I really hope they are ok."