Union flag raised in Belfast as disorder continues January 9, 2013 -- Updated 0943 GMT (1743 HKT) East Belfast was rocked by violence for a sixth straight night Tuesday, as fireworks and petrol bombs were thrown at police . Union flag is raised over Belfast City Hall for the first time since a controversial vote It is flying to mark the birthday of the Duchess of Cambridge Violent protests roil East Belfast for a sixth night, but are smaller than on previous nights Unionist leaders plan to hold a "Unionist Forum" Thursday to address grievances Belfast, Northern Ireland (CNN) -- The Union flag was raised over Belfast City Hall on Wednesday morning for the first time since a vote last month to stop flying it year-round prompted violent protests in Northern Ireland. The flag is flying because it's the birthday of Prince William's wife, Catherine -- one of the designated days when the flag will still be flown. It will be taken down again in the evening. East Belfast was rocked by violence for a sixth straight night Tuesday, as fireworks and petrol bombs were thrown at police by pro-British flag protesters. However, the disorder was sporadic and on a smaller scale than on previous nights. The leaders of the two main unionist political parties said on Tuesday they would hold a "Unionist Forum" on Thursday at Stormont to address underlying grievances peacefully. The forum seeks "to engage with the entire unionist community and to address issues of concern. It will seek to channel unionist efforts through political means," said First Minister Peter Robinson, of the Democratic Unionist Party, and Mike Nesbitt, of the Ulster Unionist Party. It was not clear whether representatives for the protesters would attend. A number of demonstrations are planned across Northern Ireland on Friday, while on Saturday protesters are to cross the border into the Republic of Ireland to hold a demonstration in Dublin. Authorities have accused loyalist extremists of exploiting the decision last month by Belfast officials to stop the century-old tradition of flying the Union Jack over City Hall year round. The British flag has long been a flashpoint between British loyalists -- primarily Protestants who want to remain part of the United Kingdom, and Irish nationalists calling for Northern Ireland to join Ireland. 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.