An election Thursday will see Sinn Fein, an Irish nationalist party that seeks union with Ireland, become the largest group in the 90-seat Northern Ireland Assembly.
Gangs of youths threw stones and fireworks at police in Belfast who hit back with water cannons as violence flared again on the streets of Northern Ireland.
Police and politicians in Northern Ireland appealed for calm on Monday after a third night of violence that saw Protestant youths start fires and pelt officers with bricks and gasoline bombs.