Belfast (AFP) -
Leaders in Northern Ireland on Thursday jointly condemned days of rioting stemming from the territory's pro-UK community, including a petrol-bomb attack on a moving bus, as police said they were probing possible paramilitary involvement.
The British and Irish governments also denounced what was the worst unrest seen in Belfast in recent years, which erupted amid anger over apparent economic dislocation as a result of Brexit and existing tensions between the pro-UK unionist and pro-Irish nationalist communities.
'Destruction, violence and the threat of violence are completely unacceptable and unjustifiable, no matter what concerns may exist in communities,' said the Northern Ireland executive -- made up of unionist, nationalist and centrist parties.
'While our political positions are very different on many issues, we are all united in our support for law and order.'
Northern Ireland's legislative assembly interrupted its Easter break to pass an emergency motion condemning the unrest.
Pro-Irish nationalist and centrist leaders identified Brexit as one root cause and criticised London for breaking promises to the unionists.
For her part, unionist First Minister Arlene Foster refrained from her recent criticisms of the nationalist party Sinn Fein, condemning 'rioting, criminality and wanton destruction'.
'It is not in the name of the people who live in the areas,' she told lawmakers.
- 'Sectarian violence' -
In the latest disorder Wednesday, gates were set alight on a 'peace line' -- walls separating pro-Irish nationalist and pro-UK unionist communities -- and police said crowds from either side broke through to attack each other with petrol bombs, missiles and fireworks.
Police Service of Northern Ireland (PSNI) temporary assistant chief constable Jonathan Roberts said the scale and nature of the violence was unprecedented in recent years.
'The fact that it was sectarian violence and there was large groups on both sides... again is not something we have seen for a number of years,' he told reporters.
The six nights of violent incidents have left 55 police officers injured, he noted, as well as a press photographer and the driver of the bus fire-bombed Wednesday.
Roberts said children as young as 13 were suspected of involvement following encouragement from adults, and the large volume of petrol bombs used suggested 'a level of pre-planning'.
The PSNI is probing if Northern Ireland's notorious paramilitary groups were involved in the unrest.
'Whether or not paramilitary groups were involved remains an active line of investigation,' Roberts added.
- Johnson's 'fantasy' promises -
Northern Ireland endured 30 years of sectarian conflict that killed 3,500 people.
Unionist paramilitaries, British security forces and armed nationalists -- seeking to unite the territory with the Republic of Ireland -- waged battle until a landmark peace deal in 1998.
The accord let unionists and nationalists coexist by blurring the status of the region, dissolving border checks with fellow European Union member Ireland.
But Britain's shock Brexit vote in 2016 to quit the EU revived the need for border checks. A special 'protocol' was agreed that shifted the controls away from the land border, but many unionists accuse London of selling them out.
There is also outrage within the unionist community after the authorities decided not to prosecute Sinn Fein leaders for attending a large funeral last year of a former paramilitary leader, in apparent breach of Covid restrictions.
- 'Defuse tensions' -
Johnson's Northern Ireland secretary Brandon Lewis was due to fly to Belfast Thursday, where he is to meet leaders from the main parties, including Foster and deputy First Minister Michelle O'Neill of Sinn Fein, as well as faith and community advocates.
British Prime Minister Boris Johnson tweeted that he was 'deeply concerned', saying 'the way to resolve differences is through dialogue, not violence or criminality'.
Irish premier Micheal Martin also condemned the unrest, calling on 'all sides to work together to defuse tensions and restore calm'.
At Thursday's Northern Irish Assembly debate Naomi Long, justice minister for the centrist Alliance Party, spoke of feeling 'some sympathy to those people out there who feel betrayed' by the British government's Brexit policy.
She charged that Johnson had made 'fantasy' promises of 'sunlit uplands' after Britain quit the EU.
Meanwhile, with some unionist leaders demanding the EU protocol be scrapped, European Commission spokesman Eric Mamer also condemned the unrest 'in the strongest possible terms'.