December 3 decision to limit the flying of the flag to 18 days per year. The disorder has resulted in more than 100 arrests and left 66 officers injured. The flag was raised Wednesday for the first time since the controversial vote to mark the birthday of Prince William's wife, Catherine. It was lowered at the end of the day. The leaders of the two main unionist political parties met Thursday to discuss concerns within the unionist community. Northern Ireland authorities have accused loyalist extremists of exploiting the decision by Belfast officials to end the century-old tradition of flying the Union flag over City Hall 365 days a year. The British flag has long been a flashpoint between British loyalists and Irish nationalists, who want Northern Ireland to join the Irish republic. The Belfast City Council vote followed a summer of heightened tensions between Northern Ireland's Catholic and Protestant communities. Riots in September left dozens of police injured. The majority of Ireland gained independence in 1921 following two years of conflict. But six of the nine counties of the province of Ulster chose to stay in the United Kingdom, eventually becoming Northern Ireland. Police: Extremist group orchestrating violencein Belfast over Union Jack In the late 1960s, the conflict between mainly Protestant loyalists, who want Northern Ireland to remain part of the United