A father of three has been jailed for two years for sexually assaulting a 13-year-old girl in front of her two-year-old-brother.

The 46-year-old Co Limerick man, who cannot be named in order to protect the identity of his victim, was in a relationship with the 13-year-old's mother at the time of the offence in February 2007.

In a victim impact statement read out to the court, the teenager who is now 15, described how she suffers constant nightmares since the attack and said she cannot sleep without locking her bedroom door.

The court heard the girl was sexually assaulted in the sitting room of her home while her mother was at work, and while her two-year-old brother, who was the son of the accused, was also in the room.

The man continued to try to assault her as she escaped to a bedroom upstairs, where he attempted to kick the door down.

The 13-year-old raised the alarm when her mother returned from work and following a medical examination doctors confirmed her injuries were consistent with that of a sexual assault. She also suffered multiple bruising.

An offer of €10,000 by the accused to pay for the victim's counselling was refused by the family and was described as an attempt to buy his way out of a custodial sentence.

Judge Moran said given the seriousness of the details of the offence and the young age of the victim he had no alternative but to impose an immediate prison sentence.

He sentenced the accused to four years, but suspended the final two, and ordered he be put on the sex offenders' register on his release from prison.