Britain on Friday renewed appeals for calm after police in Northern Ireland faced another barrage of petrol bombs and rocks overnight in an ongoing week of violence, with fears riots will continue to ignite in the coming days.

The worst unrest of recent years in the UK-ruled province has mainly stemmed from its unionist community, angry over apparent economic dislocation due to Brexit and existing tensions with pro-Irish nationalist communities.

But Thursday night saw riot police on the nationalist side of divided Belfast pelted with projectiles as they tried to prevent a crowd moving towards pro-UK unionists.

On Friday, one man living in the unionist community in Belfast showed AFP a message said to be circulating calling for "a major escalation over the weekend".

"I'm worried about the weekend ahead," Michelle O'Neill, Northern Ireland's deputy first minister and leader of nationalist party Sinn Fein, told reporters.

"I do think it's really incumbent upon us all to be very conscious of the fact that we need to be respectful of each other."

Despite similar appeals from Ireland, the United States and the European Union, crowds of hooded youths and young men have taken to the streets nightly, injuring at least 55 police officers and setting fire to a moving bus this week.

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A bus was firebombed in Belfast / © AFP

The UK's Northern Ireland Secretary Brandon Lewis met leaders Thursday including unionist First Minister Arlene Foster and O'Neill in Belfast but political appeals have so far failed to quell the unrest.

- 'Stoking the fires' -

Rioters late Thursday hurled petrol bombs and fireworks at ranks of armoured police vehicles, as well as rocks, bricks and glass bottles.

Officers using water cannon for the first time in years drove back the surging crowds late into the night, as locals peered out of their windows to witness the spectacle.

Refusing to let rioters approach, dozens of older men and women stood at the gates of a "peace line" -- walls in Belfast separating nationalist and unionist communities.

On Wednesday night, the gates were set alight and police said crowds from either side broke through to attack each other with petrol bombs, missiles and fireworks.

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The 1998 Good Friday Agreement / © AFP

Belfast-based Nichola McKee Corner, whose journalist sister Lyra McKee was shot dead during a 2019 riot in the border city of Londonderry, said the latest more widespread unrest was "difficult to witness".

She decried political leaders in Northern Ireland, saying figureheads are "ignoring" sections of the community erupting in unrest.

"Some others have been stoking the fires," she told Irish state broadcaster RTE.

"We need good and proper leadership quickly before someone is killed."

- 'Deep-rooted' -

Until a landmark peace deal in 1998, Northern Ireland endured 30 years of sectarian conflict that killed 3,500 people.

The accord let unionists and nationalists coexist by blurring the status of the region within the EU.

But Britain's 2016 vote to quit the EU revived the need for border checks on trade, potentially undermining the 1998 pact.

A special "protocol" was agreed that shifted controls away from the Irish land border to ports trading with the UK mainland. It took effect on January 1, prompting many unionists to accuse London of betrayal by diluting Northern Ireland's status in the UK.

There was also recent outrage among unionists after the authorities decided not to prosecute nationalist Sinn Fein leaders for attending a large funeral last year of a former paramilitary leader, in apparent breach of Covid restrictions.

"Brexit is a big part of it," one unionist -- who asked not to be identified -- told AFP of the recent unrest.

"I feel like the mainland UK have literally sold us out," he added. "A border down the Irish sea is another stepping stone towards a united Ireland."

Unionist Jim Matier, 74, said he believed the unrest was largely sparked by the Sinn Fein funeral decision.

But he said the Brexit protocol is part of a "slippery slope" emerging towards a united Ireland.

"Some of our politicians, I don't think are doing enough or saying enough," he said.

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