A "substantial" bomb was found in a housing estate in Northern Ireland's second city Londonderry that appears to have been designed to kill police officers, a senior officer said on Tuesday.
The bomb was found on Monday after an anonymous caller to a local newspaper claiming to be from a dissident Irish nationalist group said a device had been planted.
"We believe that the bomb is there with the intent to kill police officers," Police Superintendent Mark McEwan told reporters.
A 1998 peace agreement largely ended more than three decades of violence in which more than 3,600 people died and established a power-sharing local administration of Catholic and Protestant parties.
But dissidents opposed to the deal maintain a sporadic campaign of violence in an attempt to achieve the end of British rule in Northern Ireland and a united Ireland.
The dissident groups have been especially active in the Londonderry area in recent months and have tried luring police into areas where booby trap bombs have been planted.