A TROUBLED 17-year-old girl, who took part in a spate of vicious phone robberies in Dublin city-centre, has been detained for three months.

Judge John O'Connor imposed a six-month detention-supervision order, which means the girl will serve a three-month custodial sentence followed by another three months of post release supervision.

Judge John O'Connor told the girl, who is in care, that she will have to comply with directions of the Probation Service on her release. Otherwise she would go back into detention, he warned.

The Dublin Children's Court heard that there had been several adjournments to monitor the girl's progress, seven probation reports as well as numerous welfare reports had been prepared and the girl had continued to be troublesome in her care accommodation and repeatedly broke bail conditions.

Gardai and youth care workers had concerns for the welfare and safety of the girl who had also failed to attend an adolescents' mental health service to address her anger management problems.

The teen, who had been accompanied to her hearing by care staff and her lawyer, sat silently throughout the hearing and showed no emotion as the sentence was passed.

The girl had earlier been described by the judge as vulnerable and he had said she had a lot of issues "both family and otherwise" while a Probation Service report has found that she is in "the high risk category of re-offending".

Judge O'Connor had been told that on the morning of September 1, 2012 at St John Rogerson's Quay the girl approached a woman, "grabbed her by her hair with both hands and pulled her to the ground".

The teen fled but was arrested at Custom House Quay but had flung a phone, which was taken from the woman, into the Liffey, "just prior to being stopped by gardai".

On October 6, 2012 at the Liffey Boardwalk, she approached another woman "grabbed her by the air, took a mobile phone and fled".

She also admitted robbery of a man who had his smart-phone taken during an incident in Dublin city-centre in September 2012.

And the court heard that on another date, the girl, who has no prior criminal convictions, had been drunk and was "picking fights with members of the public".

The juvenile court had heard that the girl had sparked massive concerns for her safety when she absconded from a children's care home. In determining the length of the sentence, the judge said had taken into consideration her age at the time of the offences.