Police have fired baton rounds and deployed water cannon on rioters as violence linked to the Union Flag row flared in east Belfast yet again.
Officers were attacked with petrol bombs, paint bombs, fireworks and heavy masonry while rioters damaged vehicles with hatchets and sledge hammers. In the five nights of rage, more than 60 police officers have been injured and around 100 people arrested.
Theresa Villiers, secretary of state for Northern Ireland told BBC Radio 4 Today that Belfast and Northern Ireland were being "held to ransom".
Loyalists set up burning barricades on the Newtownards Road in Belfast
"It's not acceptable that those who say they are defending a union flag are actually doing it by hurling bricks and petrol bombs at police. It's disgraceful, frankly," she said.
"All these protests have to stop altogether, even the peaceful protests are causing disruption and even they are making it far more difficult to have a proper dialogue to resolve these kinds of issues."
"Not only is it disgraceful in terms of injuries to police officers and people who live in the areas affected by the riots, it's also doing huge damage to Northern Ireland's image abroad".
The Shadow Secretary of State for Northern Ireland, Vernon Coaker told the BBC's Good Morning Ulster it was "an issue of national security and I think we need, and the secretary of state will need, to make an assessment of what the chief constable has said about that and what needs to be done."
It was the fifth successive night that trouble raged in the area, following a largely peaceful protest outside Belfast City Hall by loyalists.
The disorder erupted as around 250 demonstrators from east Belfast returned from the city centre past a volatile community interface at the republican Short Strand.
Police said a number of missiles were thrown at the protesters, where around 70 youths had gathered.
The trouble soon spiralled from there as police moved to separate rival factions. Protesters constructed a barricade in the middle of the road and set it on fire.
Police deployed water cannon and five baton rounds were fired. Calm was restored around 10pm.
Loyalist Flag protestors, converge on Belfast City Hall, a month after the City Council decided to fly the union flag on designated days only
The earlier demonstration at Belfast City Hall came as the council met for the first time since its controversial decision to limit the flying of the flag on the roof.
Loyalist protests have been continuing across Northern Ireland since early December in response to the vote by Belfast councillors to only fly the flag above City Hall on designated days instead of all year round.
The first of these days is this Wednesday, when the flag will be raised to mark the birthday of the Duchess of Cambridge.
The Belfast Telegraph has reports of shots being fired at police officers by activists over the weekend, with Terry Spence, the chairman of the Police Federation, described the alleged gunfire as a "very sinister development". He said: "Paramilitaries have hijacked this flags protest issue and they have turned now their guns on the police."
Northern Ireland Chief Constable Matt Baggott claimed senior members of the paramilitary Ulster Volunteer Force had been orchestrating the street violence.
Elected representatives from all sides and some representing areas beyond Belfast have received death threats. The latest was against SDLP Assembly member for Mid Ulster Patsy McGlone.
A burning barricade on the Newtownards road area of Belfast
A parcel containing a sympathy card referring to McGlone and a bullet was intercepted at a postal sorting office.
Sinn Fein's Jim McVeigh accused unionist politicians of failed leadership and said they had allowed themselves to be "led by the nose" by a small band of extremists.
He said councillors would not "be intimidated by those threats.
"Their protests are pointless and they will have absolutely no impact on decisions that we take."
Democratic Unionist councillor for east Belfast Robin Newton accused Mr McVeigh and Sinn Fein of "bulldozing" the flag vote through council. "It was purely a political decision, a pure political decision," he said.