A pipe bomb, and several blast bombs and petrol bombs were thrown at police in Belfast last night in a fourth successive night of violence following the decision to ban an Orange Order parade.
The clashes between loyalist protesters and police were centred around the Woodvale Road area in the north of the city.
Police used plastic baton rounds and deployed water canon after 400 extra police were drafted in from the United Kingdom on Saturday.
In total, 44 police officers were injured in violence over the weekend, which was sparked on Friday by a decision to ban a loyalist parade from passing through the nearby republican Ardoyne area.
Commenting on the pipe bomb, which exploded on the Crumlin Road at around 5pm, Police Service of Northern Ireland Superintendent Emma Bond said: "We consider ourselves extremely fortunate that we are not dealing with a much more serious incident and that all of the officers were able to walk away from that situation unharmed.
"We have appealed for calm in the area and I continue to do so.
"I would appeal to anyone with influence in the community to exert it to ensure that the next few days pass off without incident."
Northern Ireland Secretary of State, Theresa Villiers, condemned the attack as "deplorable".
Sinn Féin assembly member Gerry Kelly branded the incident as "completely unacceptable" and "not supported by the vast majority of the community in Ardoyne."
Officers also advised the public to avoid the Broadway and Glenmachan Street areas in the south of the city where around 50 people gathered and threw stones and other missiles at police.
Police confirmed there were also reports of trouble in the Newtownards Road and Templemore Avenue areas of east Belfast.
Stormont's Justice Minister David Ford appealed to young people to not get involved in the violence.
"To young people in particular I would say this: 'Do you want to leave home today with a clean record and by tonight have a criminal record, which could have consequences which will stay with you for the rest of your life?'," he said.
"My message is clear; do not get involved in rioting on our streets, but if you choose to do so then be prepared to face the courts within hours."