UK's Boris Johnson calls for calm in Belfast as rioters hijack bus and attack police

Political leaders in Northern Ireland have put aside their differences to call for calm after the worst rioting seen in the British province for years.

Hundreds of young people in Belfast on Wednesday night set a hijacked bus on fire, attacked police with stones and hurled petrol bombs in the streets, reviving memories of decades of sectarian and political strife that claimed about 3,600 lives prior to a 1998 peace deal.

The latest violence saw eight police officers injured and boys as young as 13 and 14 arrested on rioting charges.

Northern Ireland's power-sharing executive - led by rival pro-Irish Catholic nationalists and pro-British Protestant unionists - said it was "gravely concerned" by the recent street violence.

"While our political positions are very different on many issues, we are all united in our support for law and order and we collectively state our support for policing," it said.

UK Prime Minister Boris Johnson also condemned the disorder.

"The way to resolve differences is through dialogue, not violence or criminality," he said.

Police Service of Northern Ireland Assistant Chief Constable Jonathan Roberts said it was likely that paramilitary organisations were involved in and had planned Wednesday's rioting.

He said several hundred people were on each side of a barrier separating loyalists and nationalists at a juncture in west Belfast.

"Last night was at a scale we haven't seen in Belfast or further afield in Northern Ireland for a number of years," he said.

"We are very, very lucky no-one was seriously injured or killed last night given in particular the large number of petrol bombs thrown."

More than 50 police officers have been hurt in violence in several areas since the end of last month.

Irish Foreign Minister Simon Coveney said the violence needed to stop "before somebody is killed or seriously injured".

"These are scenes we haven't seen in Northern Ireland for a very long time, they are scenes that many people thought were consigned to history and I think there needs to be a collective effort to try to diffuse tension," he told RTE.

There is growing frustration among many in the pro-British unionist community at new trade barriers between Northern Ireland and the rest of the UK following Britain's exit from the EU.

The pro-British Democratic Unionist Party has also criticised a decision by police not to prosecute Irish nationalists Sinn Fein for a large funeral last year that broke Covid-19 regulations.

Sinn Fein has blamed the DUP for stoking tension with its staunch opposition to new trading arrangements and the call in recent days for the region's police chief to step down.

Police said some of the violence was influenced by "criminal elements" who helped to orchestrate the attacks.

The violence on Wednesday took place near Shankill Road in west Belfast, near the "peace wall" that divides it from the Irish nationalist stronghold of the Falls Road, where groups of youths also gathered.

The walls and fences were built between the two communities to prevent clashes during three decades of sectarian violence in Northern Ireland that largely ended with the 1988 peace deal.

The leaders of Sinn Fein and the DUP condemned the violence, particularly the bus hijacking and an attack on a photojournalist from the Belfast Telegraph.

"This is not protest. This is vandalism and attempted murder. These actions do not represent unionism or loyalism," DUP leader Arlene Foster said on Twitter.

"They are an embarrassment to Northern Ireland and only serve to take the focus off the real law breakers in Sinn Fein," she said.