The Twelfth: More than 3,000 police officers on duty

Police watch Orangemen pass St Patrick's Church in north Belfast

More than 3,000 police officers are on duty at Orange Order parades across Northern Ireland.

Nearly half of them are members of public order units, commonly referred to as riot police, to be deployed to combat any violence.

The greatest concentration is in Belfast, where up to 1,800 officers will be on duty throughout the city.

They include 39 public order units, consisting of around 950 officers.

'Significant operation'

The majority of those units will be deployed or placed on standby in north and east Belfast, the areas where the risk of violence is considered to be highest.

The areas causing most concern are the Ardoyne area of north Belfast, where the return parade to Ligoniel will be stopped by police, and the Lower Newtownards Road and Short Strand, where there were violent clashes last year.

Earlier, there was a large police presence in north Belfast with dozens of officers and police vehicles lining the flashpoint area near to the Ardoyne shops.

Nationalist residents groups staged a peaceful protest as the Ligoniel lodge marched past. The parade was restricted to 250 people and a single drum beat, which was observed.

Later, a single drumbeat was played as the parade passed St Patrick's Church in Donegall Street.

However, one band, Finaghy True Blues from south Belfast, played a tune going past the Catholic church, in spite of a Parades Commission determination that only a single drumbeat should be played.

They admitted they had played the hymn How Great Thou Art and said they were only playing religious music outside a place of worship.

Thousands of Orange Order members are attending 18 demonstrations across Northern Ireland on Monday.

The parades mark the 325th anniversary of King William III's victory at the Battle of the Boyne in 1690.

Police sources have said they remain hopeful that there will not be serious violence at any parades on Monday, but are prepared to deal with trouble if it occurs.

Assistant Chief Constable Stephen Martin said a "significant security operation" was in place in the Ardoyne and Twadell area of north Belfast.

The outward leg of the Orange Order parade in north Belfast passed off without incident

The Orange Order has again been barred from parading along a stretch of the Crumlin Road in north Belfast that separates unionist and nationalist communities, on its return from the commemorations.

'Rights'

"The determination says that the band and the lodge can march down the road, but there are also determinations in place in respect of protests and we want to ensure that the protest activity can take place and that they're allowed to protest against the parade," he said.

"It's about upholding people's rights and ensuring that no violence accrues and that everybody behaves responsibly and it passes off peacefully."

ACC Martin said there were 601 parades taking place across Northern Ireland on Monday.

"Thirty-four of them are marked sensitive by the Parades Commission and the overwhelming majority, if not all in fact, will pass off without incident and very, very peacefully," he said.

If public order units are deployed, they will have what the police call "a full range of tactical options" available.

Those include the use of barriers, plastic baton rounds, water cannon and dogs.

Rehearsed

The police will also have air support, and specialist firearms units will be available to respond to any firearms attacks.

While tactics and operational plans for dealing with violence have been drawn up and rehearsed, police sources have said there has been "significant and wide ranging engagement" in recent months to help ensure they will not be needed.

The engagement includes discussions with senior members of the Orange Order, politicians, clergy, and community representatives, including members of the UVF and UDA.

Thousands are expected at 18 demonstrations across Northern Ireland on Monday

The issue causing most concern for the police is a statement by the Orange Order that its members will not act as marshals for the north Belfast parade.

The UVF and UDA have also indicated that they will not provide "community stewards".

The presence of such stewards has traditionally reduced the risk of violence, and signalled to potential trouble makers that they do not have the backing of loyalist paramilitaries.

Senior police officers have been lobbying the Orange Order to reverse its decision and agree to marshal the north Belfast parades, and to encourage others with influence within loyalist communities and the UVF and UDA to support their position.