Security sources believe that paramilitaries opposed to the IRA ceasefire planted a pipe bomb near the back entrance of the Dáil on Merrion Square, to mark a visit by British prime minister Tony Blair to Dublin for a meeting with Taoiseach Bertie Ahern on the Northern Ireland peace process.
An Army bomb disposal unit carried out a controlled explosion on the device, which had been left attached to the railings of a building next to the National Museum.
A telephone warning using a recognised codeword was made to the Samaritans at 6.40am yesterday morning. The caller also claimed two other bombs had been placed outside the British embassy in Ballsbridge and at the Department of Foreign Affairs on St Stephen’s Green. However, a subsequent search of those two locations revealed no suspect devices.
Merrion Square West was cordoned off for several hours as Army experts used the mechanical robot, Hobo, to study the bomb.
It was attached to railings at No 88 Merrion Square, a Georgian building owned by the National Gallery.
“Although pipe bombs are crude devices, there was certainly some level of expertise in the assembly of the one found in Dublin yesterday,” said one source.
Supt Tom Conway of Pearse St Garda Station said the warning call would also be studied in an attempt to find those responsible for the attack, while detectives are also expected to examine video footage from CCTV security cameras operating in the area.
Gardaí believe the pipe bomb may have been left some distance from the Dáil itself as there is a regular security patrol outside the back entrance to Leinster House as well as the adjacent Government Buildings which house the Taoiseach's offices.
The bomb posed no threat to Mr Blair as his meeting with the Taoiseach was being held at Farmleigh in the Phoenix Park several miles away.
Material recovered from the controlled explosion was taken away for further examination by Garda forensic experts.
A similar device was discovered outside a government building in Belfast before Monday’s marathon.