Petrol bombs have been thrown at two houses in counties Armagh and Antrim, police say.
Three Polish men escaped injury in a racist attack on their Co Armagh home. A petrol bomb was hurled at the front of the house in Portadown as the east European workers slept.
The front porch of the house in the Armagh Road suffered scorch damage, but the flames did not spread.
In a separate attack a house in the village of Mosside near Ballymoney, Co Antrim was damaged in another petrol bomb attack.
The occupants were uninjured. One man was was arrested for questioning about the bombing, which came two nights after an attack on the pub next door.
Meanwhile in Derry the all clear was given by army bomb disposal experts after a blast bomb attack on a bar in the city centre.
A device was thrown at the bar late last night. No one was injured but windows and a door in a near by house was damaged.
The security forces sealed off the area for several hours and evacuated a number of homes while a second device was examined - it was later declared to be a hoax.