Five PSNI officers were injured when they were attacked by a crowd of 100 loyalists in Newtonabbey last night.
The trouble broke out just after 8.30pm, according to a police spokesman. A building containing the constituency office of Justice Minister David Forde was targeted by the rioters and a number of windows were smashed. A car was also set alight in the violence.
The Alliance Party has borne the brunt of anger linked to a decision to restrict the number of days the Union flag flies over Belfast City Hall.
An office belonging to another Alliance Party politician, Stewart Dickson in Carrickfergus, was destroyed by arsonists in December. The party's only MP, Naomi Long, and a number of local councillors have also received death threats.
Last week, Mr Ford said unionist parties 'drove' the flag protests. Mr Ford the Alliance party's annual conference that the DUP and the Ulster Unionist Party had cynically targeted his party and in particular the Alliance MP for East Belfast Naomi Long for crude electoral purposes.
“It seems to suit unionism better to have people worried about flags and identity, protesting at the City Hall, than have them focus on the fact that their children are leaving school without the essential skills they need to make it in today’s world, and lobbying about that at Stormont,” he added.
It emerged last month that the cost of policing the continuing union flag protests has cost more than £15 million (€17.5 million). PSNI chief constable Matt Baggott outlined the financial implications of the disturbances during a briefing to members of his oversight body, the Northern Ireland Policing Board.