Two Dublin teens have pleaded not guilty to violent disorder during an incident that saw a teenage girl knocked “headfirst” under a DART.

CCTV footage showed the 17-year-old girl falling between the platform and a train waiting at Howth junction on April 1st last year.

Three 17-year-old boys have been charged with violent disorder over the incident, with one of them also facing an extra charge of assault causing harm to the girl.

Last month at the Dublin Children’s Court, Judge Paul Kelly held that two of the boys had a peripheral role and he accepted jurisdiction in their cases.

However, he said the third boy lunged at the girl with "devastating consequences" leading to her falling headfirst under the train.

He held that this teen should be tried in the Circuit Court, which has tougher sentencing powers.

The two boys facing lesser charges today pleaded not guilty and will face their hearing in May at the Children's Court.

Judge Kelly acceded to State solicitor Anna Bridgeman's request to grant more time to complete a book of evidence for the boy facing more serious allegations. He was ordered to come back in two weeks.

Earlier, Judge Kelly watched the video footage and heard an outline of the allegations from Garda Kevin O’Boyle.

He told the court 10 –15 youths “shouting and roaring” caused a disturbance on the train.

Security officers were preventing them from re-entering the train and six girls ran onto the platform to catch the Dart.

One of the boys swung his foot at a girl from his bike, making contact with her face.

One youth with a bicycle was accused of using the handlebars to lunge at a second girl striking her knee, and "as a result, she fell down off the platform headfirst".

An OCS security man raised the alarm with the train driver and pulled the girl from under the Dart train back onto the platform.

She had a cut knee and a bad cut and bruise on her back and was visibly distressed and in shock. The court heard she was in Leaving Cert year at the time and already suffering from anxiety.

The garda said she is on medication and “going through a difficult time”.

Reporting from Tom Tuite at Dublin Children's Court