Police have found a suspect device in north Belfast, after a priest received a phone call claiming a device was left for officers, but had not detonated.
Officers searched the area before carrying out a controlled explosion.
A senior police chief says the bomb was "designed to kill officers".
Security alerts have caused widespread disruption across the province.
Two people on a motorbike threw a pipe bomb into the garden of a home on Island Street in east Belfast. The bike was later found.
There is also an on-going security alert in Bramptom Park.