A 56-year-old woman has been arrested for making hundreds of threatening phone calls to politicians in the Dail and other State agencies.
The woman, described as "highly disturbed" was arrested in the Clondalkin area of west Dublin earlier today and is being detained at Pearse Street Garda Station.
Sources say that the woman is being investigated for making multiple threatening phone calls over the last number of months.
These include death threats against Environment Minister Alan Kelly and his family which have been described as "extremely menacing" by sources.
The Clondalkin woman is also being questioned about threats against Labour junior minister for justice Aodhan O Riordan as well as Clondalkin-based TD Robert Dowds.
A senior source said she is alleged to have recently made over 60 threatening calls to politicians' offices the Dail in the space of one week alone.
"The woman appears to have built up a disturbing fascination about the whole Irish Water issue," a source told the Herald.
"The threats against Minister Kelly was particularly sick in nature."
She is also being investigated for making bomb threats to An Post and threatening President Michael D Higgins and his residence at Aras an Uachtarain as well as to Tipperary Fine Gael TD Noel Coonan.
This morning's arrest followed a major garda operation in which technical experts examined phone records over the course of a number of weeks.
Gardai received a number of complaints from politicians about threatening calls to their Dail offices and other places of work which were made by a woman.
It is believed that the woman was identified in recent weeks and that gardai have built a strong case against her.
A planned search of the woman's Clondalkin home also took place this morning. She is also suspected of being involved in similar behaviour in the past targeting other individuals.
Under legislation, the sending or making of a threatening or menacing call is illegal under Section 13 of the Post Office (Amendment) Act 1951 and Section 10 of the Non-Fatal Offences against the person Act 1997.