Twenty six police officers have been injured in loyalist rioting as violence linked to a contentious republican parade engulfed Belfast city centre.
Five of the officers required hospital treatment and there were reports that a number of members of the public were also hurt.
Police fired plastic baton rounds and water cannon after coming under attack from loyalists who pelted them with bottles, fireworks and glasses as hundreds of loyalist demonstrators gathered to protest at the rally.
Officers came under "heavy and sustained attack" Metal guttering ripped from shop fronts was also used in the violence and several vehicles were set on fire.
Protesters had attempted to block part of the route of the Anti-Internment League parade, which was diverted to avoid the disturbances.
There were some sectarian clashes as the march passed close to loyalist protesters.
Assistant Chief Constable George Hamilton said: "Police have come under heavy and sustained attack by crowds intent on creating disorder.
Five offiers required hospital treatment "As disturbances are continuing I would call upon people of influence in communities and those in political leadership to do all possible to reduce tension.
"As Northern Ireland moves ahead, the effect of tonight's violence has the potential to damage the local economy and the reputation of Belfast as a tourist destination."
The disorder comes after eight officers were injured at a republican anti-internment bonfire near the city centre on Thursday night.
Police said their use of water cannon was a "proportionate" response Eight people were arrested and at one point, as violence spread to north Belfast, officers were attacked by a man with a sword.
The parade was unable to pass down Royal Avenue as intended. After a significant delay, it did finally proceed along the outskirts of the city centre and onward to west Belfast.
However, trouble continued in its wake.
Steve Pound MP, Labour's Shadow Minister for Northern Ireland, said: "We have seen sad scenes again in Belfast tonight, which have become too familiar over recent months.
Protesters attempted to block part of the route parade "The vast majority of people across the community will unite to condemn attacks on the police and the public disorder we have seen.
"But unfortunately this is not an isolated occurrence. Northern Ireland can't afford to slip back to causal violence or acceptance of it.
"Both the governments and political leaders in Northern Ireland need to show leadership and address what are becoming far too common scenes."
Last month parts of Belfast were consumed by more rioting, predominantly loyalist, when Orangemen were banned from parading past the nationalist Ardoyne area.
Eight people have been arrested so far Friday night's republican parade is in protest at the deeply controversial internment policy in place at the height of the Troubles in the 1970s.
It saw mass arrests and detention without trial of hundreds of people suspected of being involved with the IRA.
Parading tensions have also spread to other parts of Northern Ireland with controversy surrounding a planned Sinn Fein-backed commemoration event in the County Tyrone town of Castlederg on Sunday.
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