Detectives say student John Rees, stabbed to death after a birthday night out, may earlier have been caught up in a brawl on a nightclub dance floor.

The 23-year-old from Shoreham Beach died early on Sunday after being stabbed in the chest on Southsea Common, Portsmouth.

CCTV footage shows Mr Rees leaving the Pyramids Club in Southsea where he had been out celebrating a friend's birthday with fellow Portsmouth University students. From the club, John's party moved on to the common where the killer struck.

Police spokesman Kevin Briscoe said: "They were involved in a verbal dispute with a larger group of six or seven people.

"This dispute resulted in John receiving a single stab wound to the lower chest.

"John's friends tried desperately to stop the bleeding and an ambulance was called."

He was taken to the Queen Alexandra Hospital, Cosham, but efforts to revive him failed. He was pronounced dead at 4am on Sunday.

Mr Briscoe said: "Unfortunately, the area where the incident took place was pitch black. There were CCTV cameras there, but they are not infra-red. Therefore, we are unlikely to have any footage of it.

"John's friends were obviously very concerned for his welfare after the stabbing and concentrated on him, so we do not have a description of the other group."

Mr Rees had been drinking in pubs in the Guildhall Square area before moving on to the Pyramids Club where witnesses said there was a heated argument involving two groups.

A fight reportedly broke out between two men, one of whom may have been Mr Rees.

Detective Superintendent Graham Haycock, leading the murder hunt, said: "This appears to be a random and motiveless killing."

John, from Old Fort Road, was in the fourth year of his degree and had spent a year out working at Gatwick Airport.

His mother, Rosalynd, 45, said she received a call from the police early on Sunday.

She said: "We raced over to Portsmouth but it was too late. John had already died."

The ex-pupil of Blatchington Mill School, Hove, has a sister Emma, 25, and a brother, Gareth, 20.

Police are questioning a 19-year-old man in connection with John's death. The man was arrested at his home in Drayton, Portsmouth, yesterday afternoon and was taken to Waterlooville police station.

Today detectives said they had arrested a second man, also 19 and from Drayton.

He is being held at Fareham Police Station and was expected to be interviewed today.