A 10-year-old boy born with foetal alcohol syndrome has found himself at the centre of an Anglo-Irish legal debate after his adoptive parents said they were struggling to cope.

The youngster was born in England and adopted at the age of two after being taken into care by social services staff working for the Borough of Poole, a senior family court judge has heard.

Shortly afterwards his adoptive parents moved to a new home near Dublin, and the youngster lived in Ireland for more than seven years.

Earlier this year the couple returned to England and "presented" him to social services staff in Poole.

The couple said they were finding it hard to manage the youngster's behaviour and he said he needed help.

They feared he would "bounce around" the foster system if taken into care in Dublin, and said his needs would be best met in the UK.

Details of the case emerged in a ruling by Mr Justice Baker following a family court hearing in Bournemouth.

The judge said he was asked to decide whether an English or Irish family court judge should oversee the case. He concluded that the boy was habitually resident in Ireland and said an Irish judge should take the reins.

Mr Justice Baker, based in the Family Division of the High Court in London, said no-one involved could be identified.

"His birth mother used alcohol and heroin during her pregnancy and he was born with foetal alcohol syndrome," said Mr Justice Baker in his ruling.

"Unfortunately, (his adoption) placement ... has been beset with serious difficulties. In particular, his parents have struggled to manage his behaviour."

The judge added: "It is clear from the documents included in the court papers that (he) has demonstrated particularly challenging behaviour.

"Over the last eight years, he has had a variety of therapeutic help and assistance from a number of professional agencies, including occupational therapy, psychological assessment, play therapy and psychotherapy.

"He has been diagnosed as suffering from attention deficit hyperactivity disorder, mood dysregulation disorder, alcohol-related neurodevelopmental disorder, a sensory processing disorder and a reactive attachment disorder."

Mr Justice Baker said boy's adoptive parents travelled to Poole early this year and "presented him to the social services department".

"The Poole social worker described how (his adoptive mother) reported that she and her husband had made the decision not to relinquish care of (the boy) to Dublin children's services because, in their view, 'he would bounce around the foster care system and end up medicated in a residential unit and his life chances would be very poor'," said Mr Justice Baker.

"The social worker reported that (adoptive parents) were of the view that (his) needs would be best met in the UK where (he) would be able to access the therapeutic support he requires.

"(His adoptive mother) reported that they were aware of the potentially traumatic impact on (him) but felt they had no other option as their family was at breaking point."

The couple want the boy "rehabilitated" to their care in the future when he has received the "therapeutic intervention" he needs and can "function within the family", said the judge.

Mr Justice Baker said the boy has been placed in a residential unit in England pending the outcome of litigation.

The judge said he had analysed legal argument about jurisdiction before concluding the boy was an Irish resident and his case should be analysed in an Irish court.

He said he had heard from barristers Leslie Samuels QC and Sarah O'Hara, for Poole council; Sarah Morgan QC, Deirdre Fottrell QC and Louise MacLynn, for the adoptive parents; and Omar Malik, who represented the boy.