TWO police officers have been injured during trouble which erupted during a loyalist flag protest in Belfast city centre.
There is a heavy police presence in the Shaftesbury Square area where around 200 people gathered on Friday night.
So stretched are police resources that riot cops numbers in each vehicle have been reduced by almost half to cope with the rising tide of violence.
Three people were arrested on Friday night and are in custody being questioned over public order offences.
The disturbances come ahead of a protest rally on Saturday. Police believe up to 6,000 people may attend.
Police have responded to reports of a number of vehicles on fire in the Carnmoney Road North area of Newtownabbey, on the outskirts of Belfast, close to council offices at Mossley Mill.
There was also trouble on Friday evening in south Belfast, where a car was hijacked in Stroud St and at Donegall Pass.
A police water cannon arrived at the scene after bottles and other missiles were thrown at police.
A car has been set on fire on Donegall Road and another vehicle was torched at nearby Combermere Street.
Traffic was disrupted after a number of people gathered, some of whom were carrying Union flags and blocked the road.
Police advised motorists that the area is now closed to traffic and diversions are in place.
A number of small protests have also taken place in the Greater Belfast area and Bangor. A protest is also ongoing in the Ligoniel Road area in the north of the city.
The latest trouble follows a number of loyalist demonstrations across Northern Ireland this week, in the wake of a Belfast City Council vote to restrict the flying of the Union flag to 17 days a year.