Belfast erupted into violence last night at the nadir of marching season.

At least seven police officers were injured after coming under attack from crowds of rioters – predominantly youths – throwing petrol bombs and stones and bricks.

During the trouble, which flared throughout the night mainly in the west of Belfast, a bus was also hijacked and driven at a police cordon. It crashed a short distance away, according to the police force, while gunshots were also heard.

Tension has been bubbling in the Northern Ireland capital throughout the marching season. On June 21, a number of people were

injured in sectarian clashes which broke ou.

Shots fired during Belfast riots

Last night, riots broke out in the nationalist areas of Broadway, Old Park and North Queen Street and have continued throughout the early hours of this morning.

The violence in Belfast erupted as loyalists prepared for the traditional Twelfth of July celebrations which mark the 1690 Battle of the Boyne.

Tens of thousands of Orangemen and bandsmen are due to take to the streets later today as part of the annual event, which signals the height of the marching season.

When the riots erupted, police used water cannons and fired baton rounds to try and disperse crowds of around 100 and 200 people.

A number of vehicles were reportedly hijacked with a motorbike and at least one van set on fire, according to the Police Service of Northern Ireland.

Petrol was also thrown at officers in North Queen Street where around 40 people have gathered, the force said.

A bus was hijacked on the Falls Road and then driven at a police cordon separating loyalists and nationalists on the Donegall Road, but crashed before reaching officers.

A firefighter was injured and a fire appliance damaged during the riots.

Crews from Springfield fire station in west Belfast came under attack and a vehicle windscreen was smashed. A firefighter was also slightly hurt by young people throwing stones in Londonderry.

The Northern Ireland Fire and Rescue Service said it had received 180 calls up to 1am this morning – a 65 per cent increase from last year. At the busiest time, the service was taking a call every 75 seconds, with most within the Greater Belfast area.

Deputy chief fire officer Chris Kerr said the fire service would continue to engage with community representatives to ensure public safety.

"Firefighters are already exposed to significant risk, in what can be a dangerous profession, without having to face such deliberate attacks from those who they are trying to serve," he said.

The riots in Belfast broke out despite politicians and churchmen on both sides appealing for a day free of violence, especially in the aftermath of serious disturbances in loyalist areas of east Antrim at the weekend.

Security chiefs have put extra resources on standby in potential flashpoint areas of Belfast and Craigavon, Co Armagh, while every available police officer will be on duty at today's 19 separate demonstrations.

New armour-plated police Land Rovers – part of a replacement consignment of 60 which has just arrived – will give officers additional protection in areas like Ardoyne, north Belfast, where republicans opposed to the peace process have threatened protests.

The largest parade will be in Belfast where some city centre department stores are planning to open.

There has been serious violence in this area before because of local opposition to Orange parades.

The Orange Order leadership insists they are a unique opportunity to showcase its history and heritage and draw many overseas visitors.

Grand master Edward Stevenson said: "There is no other single event that can produce crowds like the Twelfth. It is such a special day of religion, culture, music and pageantry."