David Goulding, aged 29, from Whitechapel Grove in Blanchardstown, Dublin, was taken to the Bridewell district court on Thursday morning last, where he was charged with intimidating a witness.

While he was inside the court, a group of his associates clashed with another group that had also gathered outside.

A man in his mid-20s, who is from Blanchardstown and well known to gardaí, produced a hammer and attacked the group, leaving three men with broken noses and other injuries.

Gardaí inside the court heard the commotion and rushed outside to see the two groups brawling.

The man carrying the hammer fled into the nearby St Michan's House flats complex and was pursued by a female garda.

She wrestled the man to the ground and arrested him, and he was taken to the Bridewell garda station. The three assault victims required hospital treatment and have refused to give statements to gardaí. The suspect is to be charged with assault nevertheless.

It is estimated that over a dozen people were involved in the incident, and gardaí fear that there will be more attacks in retaliation.

Goulding remained in the court cells while the violence was going on. He consented to be remanded in custody until next week, when a full bail hearing will take place.

Senior gardaí are concerned that such a potentially serious incident could have happened directly outside a busy courthouse, and they plan to review security measures.

"We will either have to look at the amount of gardaí on duty around the courts or review how we take prisoners to the court building. It is not acceptable that two rival groups can openly clash and attack each other in public, " said a garda source.

The Bridewell court, opposite the Four Courts complex, is one of the busiest district courts in Dublin and hundreds of cases are processed there each day. It is also attached to a large garda station.