The gardaí have said there were indications a pipe bomb discovered in Dublin city centre this morning contained explosives.
The western side of Merrion Square was closed off for a period, while the Army carried out a controlled explosion on the device.
A 6.40am call to the Samaritans, by a person who gave a codeword, had warned that devices had been planted at three locations around the city.
Following searches at the Department of Foreign Affairs and the British Embassy, the only device - believed to have been a pipebomb - was found in the basement yard of a house beside the National Gallery on Merrion Square.
The gardaí say they are trying to establish who was responsible for the attack.
Supt John Farrelly of the Garda information office said they were treating it as a serious incident.