Police in Northern Ireland have used water cannon against loyalist protestors in East Belfast.
Rioters attacked police with bricks and petrol bombs as they tried to separate rival factions, the BBC reports.
It was the fifth successive night of violence, triggered by a decision to restrict the flying of the Union flag at Belfast City Hall.
The BBC reports that there is no prospect of the the council changing its mind on the issue - but the protesters says their campaign will continue.
Initially, 400 people attended what police described as a "largely peaceful" protest outside City Hall between on Monday.
Serious trouble broke out as about 250 of the protesters passed the Short Strand on their return to east Belfast.
A number of missiles were thrown by nationalists as they passed.
Police then came under attack as they tried to move loyalists up the Lower Newtownards Road.
The Police Service of Northern Ireland (PSNI) said five plastic bullets were discharged due to the "level of violence" that police were subjected to.
Loyalist protesters set up a barricade in the middle of the road and set it alight.
Police received reports of two attempted hijackings of a car and a lorry in the area.
Petrol bombs, fireworks and other missiles were also thrown at police during rioting on Robbs Road in Dundonald and a car was set on fire in Bute Park.
Two men and two women were arrested for riot and public order offences.
Loyalist agitators
PSNI Chief Constable Matt Baggott said individual senior loyalist paramilitaries had been involved in orchestrating violence during union flag protests in east Belfast.
Mr Baggott said there was "no excuse whatsoever" for violence.
He said if protests continued in the long-term, day-to-day policing would be affected.
This included his officers' ability to deal with the threat from dissident republicans, he added.
Sixty-two officers have been injured since the protests began.
The first of the designated flag days will be Wednesday 9 January, the Duchess of Cambridge's birthday.
Chief Constable Matt Baggott saw ''youngsters aged 10 and 11'' on the streets during protests and confirmed that since the flag protests began, 96 people had been arrested, including a "significant number" of young people.
