Further violent Catholic protests break out in Northern Ireland , police say . Nine police officers were injured a month ago . Protesters pelted officers with petrol bombs , fireworks and bricks , police say . Protests have rocked parts of Belfast since a vote on the Newtownabbey flag .
Further violent pro-British protests break out in Belfast , police say . Nine police officers were injured Friday . Protesters pelted officers with petrol bombs , fireworks and bricks , police say . Protests have rocked parts of Northern Ireland since a vote on the Union flag .