Barton (right) attacked Dabo (left) in a training ground incident

Newcastle's Joey Barton has admitted to a Football Association charge of violent conduct over his assault of former team-mate Ousmane Dabo.

In July, Barton received a four-month suspended prison sentence for the assault which occurred in May 2007 when the pair were at Manchester City.

He has requested a personal hearing to answer the charge.

There is no maximum limit to the punishment he could face but a lengthy ban and possible fine are likely.

Since the assault on Dabo, Barton has been jailed for a drunken attack on revellers in Liverpool city centre.

The �5.8m midfielder missed United's open day at St James's Park on Wednesday, where manager Kevin Keegan failed to mention Barton's absence.

Barton admitted the charge at the FA headquarters in Soho Square and requested a personal hearing before an FA regulatory commission in due course.

The 25-year-old had been sentenced after admitting assault occasioning actual bodily harm on Dabo, 31, who now plays for Lazio.

Barton was released from prison in July after serving 74 days of his sentence for attacking a teenager and Newcastle announced the club would be standing by him.

The player also missed the Magpies' pre-season trip to Palma, where the team played in the Mallorca Summer Cup.