Bomb disposal experts are examining a suspect device found under the car of a police officer in Belfast.
The security alert on the Upper Newtownards Road in the east of the city has seen a number of homes evacuated.
Army technical officers are working to establish if the device is a viable bomb.
SDLP Policing Board member Conall McDevitt condemned the apparent bid to target the officer:
This is a cynical and deplorable act.
Those seeking to target police officers are undermining not only the stated will of the people of Ireland who have long since rejected violence, but also the desire for a new beginning for policing in the North, which is shared by the majority of citizens.
More top news
The PM faces a countdown to settle a deal before her minority government tries to get its Queen's Speech plans approved by the Commons.
More details will come today on proposals to offer EU residents the right to a new "settled status" in Britain after it leaves the bloc.
Scotland and Northern Ireland could see rain later but for the rest of the UK it should be a fine day.