After five days of nightly violence in east Belfast, police are gearing up for a tense day as the Union Flag is flown for the first time since the controversy over its use, to mark the Duchess of Cambridge's birthday.

The occasion of Kate's birthday is one of the United Kingdom's official "flag days."

All Royal birthdays are marked, with spouses like the Countess of Wessex and Camilla, Duchess of Cornwall, included.

Other occasions traditionally marked by the flying of the flag is the Queen's wedding anniversary, her actual birthday and her official birthday, which are on different days.

Last month, Sinn Fein, the Social Democratic and Labour Party (SDLP) and the cross-community Alliance Party all voted to limit the number of days the flag flies at City Hall, with all unionist members of the council opposing the move.

The flag will no longer fly continuously, but only on appointed days. A list of official days is on the Departement for Culture, Media and Sport's website.

Nationalist councillors had asked that the flag not to be flown at Belfast City Hall at all.

The Duchess of Cambridge's 31st birthday will be the first time the flag has been flown since the crisis.

union flag

Loyalist Protestors converge on Belfast city hall.

On Monday night, in a fierce debate over raising the flag at the height of the tensions, opposing politicians accused each other of political game-playing over the birthday flag-raising.

The flag issue was not on the formal agenda of last night's Belfast City Council meeting, but councillors did spend an hour debating the matter.

Democratic Unionist councillor for east Belfast Robin Newton accused McVeigh and Sinn Fein of "bulldozing" the flag vote through council.

"It was purely a political decision, a pure political decision," he said, rejecting the claims that unionists had not shown leadership.

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  • Union Flag protests

    Loyalist Flag protestors, converge on Belfast City Hall, a month after the City Council decided to fly the union flag on designated days only.

  • ADDS DATE - Loyalists set up burning barricades on the Newtownards Road in Belfast, Monday, Jan. 7, 2013, a month after the City Council decided to fly the union flag on designated days only. Protesters have been out in force — with sometimes violent results — since a Dec. 3 decision by Belfast City Council to stop flying the British flag year-round. Such issues of symbolism frequently inflame sectarian passions in Northern Ireland, where Protestants mainly want to stay in the United Kingdom and Catholics want to unite with the Republic of Ireland. (AP Photo/PA, Paul Faith) UNITED KINGDOM OUT NO SALES NO ARCHIVE PRESS ASSOCIATION Photo. Picture date: Monday January 7, 2013. See PA story ULSTER Protests. Photo credit should read: Paul Faith/PA Wire

  • Police use water cannon to disperse rioting Loyalists on the Newtownards Road in Belfast, Monday, Jan. 7, 2013, a month after the City Council decided to fly the union flag on designated days only. Protesters have been out in force — with sometimes violent results — since a Dec. 3 decision by Belfast City Council to stop flying the British flag year-round. Such issues of symbolism frequently inflame sectarian passions in Northern Ireland, where Protestants mainly want to stay in the United Kingdom and Catholics want to unite with the Republic of Ireland. (AP Photo/PA, Paul Faith) UNITED KINGDOM OUT NO SALES NO ARCHIVE PRESS ASSOCIATION Photo. Picture date: Monday January 7, 2013. See PA story ULSTER Protests. Photo credit should read: Paul Faith/PA Wire

  • Loyalists set up burning barricades on the Newtownards Road in Belfast, a month after the City Council decided to fly the union flag on designated days only. Protesters have been out in force — with sometimes violent results — since a Dec. 3 decision by Belfast City Council to stop flying the British flag year-round. Such issues of symbolism frequently inflame sectarian passions in Northern Ireland, where Protestants mainly want to stay in the United Kingdom and Catholics want to unite with the Republic of Ireland. (AP Photo/PA, Paul Faith) UNITED KINGDOM OUT NO SALES NO ARCHIVE PRESS ASSOCIATION Photo. Picture date: Monday January 7, 2013. See PA story ULSTER Protests. Photo credit should read: Paul Faith/PA Wire

  • Union Flag protests

    Loyalists confront police in Belfast, a month after the City Council decided to fly the union flag on designated days only.

  • Union Flag protests

    Loyalists set up burning barricades and on the Newtownards Road in Belfast, a month after the City Council decided to fly the union flag on designated days only.

  • Union Flag protests

    Loyalist Flag protestors, converge on Belfast City Hall, a month after the City Council decided to fly the union flag on designated days only.

  • Union Flag protests

    A Loyalist Flag protestors, on the wall of Belfast City Hall, a month after the City Council decided to fly the union flag on designated days only.

  • Union Flag protests

    Loyalist Flag protestors, converge on Belfast City Hall, a month after the City Council decided to fly the union flag on designated days only.

  • Union Flag protests

    Loyalist Flag protestors, converge on Belfast City Hall, a month after the City Council decided to fly the union flag on designated days only.

  • Union Flag protests

    Loyalists set up burning barricades and on the Newtownards Road in Belfast, a month after the City Council decided to fly the union flag on designated days only.

  • Union Flag protests

    Loyalist Flag protestors, sitting in a bus shelter near to Belfast City Hall, a month after the City Council decided to fly the union flag on designated days only.

  • Union Flag protests

    A Loyalist Flag protestors, on the wall of Belfast City Hall, a month after the City Council decided to fly the union flag on designated days only.

  • Union Flag protests

    Loyalists block the Sandy Row area of Belfast, other roads across they city were also blocked tonight as part of a mass protest over flags. The pickets caused disruption for rush hour traffic. Bus operator Translink said it was suspending most of its Metro services into and out of the city centre.

  • Union Flag protests

    Loyalists block the Sandy Row area of Belfast, other roads across they city were also blocked tonight as part of a mass protest over flags. The pickets caused disruption for rush hour traffic. Bus operator Translink said it was suspending most of its Metro services into and out of the city centre.

  • Union Flag protests

    Loyalists block the Sandy Row area of Belfast, other roads across they city were also blocked tonight as part of a mass protest over flags. The pickets caused disruption for rush hour traffic. Bus operator Translink said it was suspending most of its Metro services into and out of the city centre.

  • Union Flag protests

    Loyalists block the Sandy Row area of Belfast, other roads across they city were also blocked tonight as part of a mass protest over flags. The pickets caused disruption for rush hour traffic. Bus operator Translink said it was suspending most of its Metro services into and out of the city centre.

  • Union Flag protests

    A Christmas shopper makes her way between Police and Loyalist protestors ,at Belfast City Hall.

  • Union Flag protests

    Police keep Loyalists protestors on the footpath at Belfast City Hall.

  • Union Flag protests

    Loyalists protestors at Belfast City Hall.

  • Union Flag protests

    Protesting Loyalists block a road in east Belfast.

  • Union Flag protests

    A Police Landrover with the remains of a petrol bomb, thrown by protesting Loyalists in east Belfast.

  • Union Flag protests

    A burned out car during disturbances which erupted in east Belfast, with police coming under attack for a fourth night in a row.

  • Union Flag protests

    Police on patrol during disturbances which erupted in east Belfast, with police coming under attack for a fourth night in a row.

  • Union Flag protests

    A burned out car during disturbances which erupted in east Belfast, with police coming under attack for a fourth night in a row.