The complaint against the priest was initially made to the Health Service Executive (HSE), which then forwarded the information to the diocese which in turn contacted the gardaí.
It is understood the complaint may date back many years.
Canon Liam O’Driscoll, who is child protection director for the diocese, confirmed that a complaint of a child protection nature had been made against an unnamed priest.
He said the allegation did not relate to any incident in the parish the priest is currently serving in.
The priest had served in a number of other parishes in the diocese before moving to his present parish.
“The complaint has not been established as either true or false,” Canon O’Driscoll said.
He said in accordance with diocesan child safeguarding policy the priest had been asked to stand aside temporarily while the matter is being investigated.
“All complaints of this nature are dealt with according to Church and state guidelines in which the safety and wellbeing of children is of paramount consideration,” the canon said.
The diocese has confirmed he is the only priest serving there who is under Garda investigation.
Last December Bishop John Buckley revealed that between 1970 and 2009 a total of 14 priests in the diocese had been investigated over abuse claims and the diocese has paid €152,368 in compensation.
The compensation was paid out from 1990, although the bishop didn’t say how many victims had received money.
Bishop Buckley said the money was paid from an independent trust and it also funded “therapeutic assistance” to help victims overcome their trauma.
Bishop Buckley released the figures in the wake of the Dublin inquiry.
The bishop said that during the past two years, a series of training courses have been put in place for lay people who have volunteered to become local/parish safeguarding representatives.