Dabo was left requiring hospital treatment for cuts to his face following the incident, which erupted during a training game at City's Carrington training complex.

Manager Stuart Pearce reacted swiftly and, in conjunction with chairman John Wardle and chief executive Alistair Mackintosh, has banned Barton for the remainder of the season.

Coming just five days before the Manchester derby, it is the last thing Pearce needed and only adds to a miserable campaign in which there have been problems on and off the pitch.

Barton, 24, will face an internal disciplinary hearing at some point in which he will be asked to explain his actions.

It is hard to see how the England international can justify his behaviour and is at odds with the mild-mannered approach he appeared to be adopting on the field after undergoing behavioural counselling at the renowned Sporting Chance clinic.

Only last week, Barton caused a minor sensation with an emotional and outspoken attack on the way City was being run.

In a wide-ranging interview, the Merseysider heavily criticised some of City's new signings - Dabo among them - for failing to produce the goods this season, attacked the lack of planning at boardroom level and then claimed he would not have paid to watch the Blues play if he had been a fan.

Amazingly, Barton escaped any sanction for his tirade, which Pearce admitted was unhelpful.

However, the latest problem is on a far bigger scale and brings back instant reminders of regrettable incidents that have dogged his past.

In 2004, Barton was fined a club record six weeks' wages for an attack on team-mate Jamie Tandy. During the players' Christmas party, Barton stubbed out a cigar in Tandy's eye, drawing widespread condemnation from inside and outside the club.

Although the player vowed to change his ways, he ended up in more trouble during City's pre-season tour of Thailand in the summer of 2005.

In a hotel bar in Bangkok, the Huyton-born player physically attacked a schoolboy Everton fan and had to be restrained by team-mate Richard Dunne.

Barton was subsequently sent home in disgrace and fined eight weeks' wages, with Pearce admitting at the time he was tempted to allow the local police to take him away and throw him into prison.

Having stood by him so publicly, Pearce then had the support thrown back in his face at the end of the following January transfer deadline when he slapped in a request to leave the club, angered by what he perceived to be an insulting contract offer.

Barton eventually made his peace with the club and signed a four-year contract last summer.

Since then, he has largely managed to stay out of trouble, in the process becoming one of the most important players in City's squad.

His outstanding midfield performances were recognised at the highest level by Steve McClaren in February when he handed Barton his England debut in the friendly defeat to Spain.

Even that appearance did not come without controversy though, with Barton lambasting many of his new international team-mates for bringing out autobiographies of the back of woeful performances at the World Cup.

Barton has vowed only to go into print when he has a story to write. But this chapter will not make pretty reading for anyone connected with the player, although his agent Willie McKay has attempted to defend Barton.

McKay told BBC Sport: "As far as I've heard, he was defending himself. But because it is Joey it makes headlines."

McKay added: "It happens on training grounds all over the country, from Chelsea to Yeovil."