Rioting flared tonight when an Orange parade skirted the flashpoint Garvaghy Road in Portadown, Co Armagh.
Several RUC officers were hurt in disturbances which saw petrol and acid bombs thrown and a car pushed into a line of police vehicles and set alight, a police spokeswoman said.
Republicans said at least a dozen plastic bullets were fired and said the fight was provoked by loyalists breaking parade restrictions and RUC heavy-handedness.
Sinn Fein Assembly Member Dara O'Hagan criticised the Parades Commission for ignoring its appeals to halt the Parkmore Junior Orange march further away from the overwhelmingly Catholic Garvaghy Road.
The annual march passes the bottom of the road - as opposed to the top where Orangemen at Drumcree Parish Church have been banned from marching since 1998.
Police said today's march itself passed off without incident but that groups of men and youths confronted officers on public order duty. PA