9 January 2013 Last updated at 17:54 ET

Union flag lowered in Belfast after flying for royal birthday

The BBC's James Cook says police are hoping the situation remains calm

Belfast City Hall's union flag has been lowered after flying for the first time since a decision was taken not to display it permanently.

The vote by Belfast city Council on 3 December sparked a campaign of protests, some of them violent.

The flag flew on Wednesday to mark the Duchess of Cambridge's 31st birthday.

Flag protests have taken place in Belfast and Londonderry on Wednesday evening, but there have been no reports of any trouble.

The Northern Ireland secretary of state has said riots linked to the protests are causing "significant damage" to the economy.

Theresa Villiers said the "negative images" were "threatening jobs".

'Incomprehensible'

She described the violence as "appalling".

Analysis Mark Devenport Political editor, Northern Ireland

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Seen from afar, riots over which flag flutters above a council building may appear inexplicable.

However, national identity remains a source of deep division in Northern Ireland.

Disputes about flags and symbols have been a regular occurrence over the decades.

• Read more from Mark

"Those who have been trying to bring Northern Ireland to a standstill need to take a long, hard look at what it is they think they're achieving," she said.

"I can understand that feelings run high when it comes to issues on flags, particularly in Northern Ireland where questions of identity remain so sensitive.

"But nothing can excuse the scenes we have witnessed, with over 60 police officers injured."

Ms Villiers said it was "incomprehensible" to express patriotism and support for the union by "hurling bricks and petrol bombs at police".

"These violent protesters are damaging the cause they claim to support," she said.

The cost of policing the protests is believed to be over £7m.

Some of the protests have been violent and resulted in more than 100 people being arrested and dozens of police officers sustaining injuries.

Loyalists have made it clear they will continue their protests.

Their central demand is for the decision to fly the union only on designated days to be reversed but the political make up of the council means there is little chance of that happening.

Meanwhile, the chairman of the Families Acting for Innocent Relatives group has said a planned loyalist protest in Dublin on Saturday will not take place as scheduled.

Barry Halliday, who was assisting loyalist activist Willie Frazer in organising the protest, told RTE News that it had been "put on hold" following contact with Irish police.

DESIGNATED DAYS FOR FLYING THE UNION FLAG*
*Source Department of Culture, Media and Sport and subject to review
9 January	Birthday of The Duchess of Cambridge
20 January	Birthday of The Countess of Wessex
6 February	Her Majesty's Accession
19 February	Birthday of The Duke of York
10 March	Birthday of The Earl of Wessex
11 March	Commonwealth Day (second Monday in March)
17 March	St Patrick's Day (in Northern Ireland only)
21 April	Birthday of Her Majesty The Queen
9 May	Europe Day
2 June	Coronation Day
10 June	Birthday of The Duke of Edinburgh
15 June	Official Celebration of Her Majesty's Birthday
21 June	Birthday of The Duke of Cambridge
17 July	Birthday of The Duchess of Cornwall
15 August	Birthday of The Princess Royal
10 November	Remembrance Day (second Sunday)
14 November	Birthday of The Prince of Wales
20 November	Her Majesty's Wedding Day
Not applicable to Northern Ireland are the opening and closing of Parliament and the English, Scottish and Welsh national saints' days