Northern Ireland braced Wednesday for a potential second night of violence directed at immigrants, following unrest that UK authorities say was stoked by far-right activists on social media after a brutal Belfast stabbing.

The Northern Irish capital's centre was largely deserted by late afternoon, with restaurants and shops shuttered and public transport poised to close amid fears of a repeat of Tuesday night's disorder.

But the main flashpoints 24 hours earlier appeared quiet as evening approached, with some schools shutting early and police bolstering their presence on the city's riot-scarred streets. 

Earlier, a Sudanese man appeared in court over the knife attack that triggered the overnight unrest, which also spread to the Scottish city Glasgow.

In Belfast, masked rioters torched vehicles and buildings and forced families to flee their homes.

UK Prime Minister Keir Starmer condemned the scenes as "shocking and completely unacceptable".

Meanwhile the family of Stephen Ogilvie, the victim of Monday night's horrific stabbing warned against using the "terrible tragedy" to "divide people or fuel hostility".

In a statement released on the Facebook page of a local politician, they appealed for calm. 

It comes with tensions already high across the UK. There were skirmishes in southern England last week over the police handling of the murder of a white student by a British Sikh man.

Anselme Shima, originally from the Democratic Republic of Congo, and who has lived in Northern Ireland since 2013, called the situation "terrifying".

"I have two children at home and this morning I am wondering, 'Can I send them to school?'" the 48-year-old told AFP.

Court appearance

At Belfast Magistrates' Court on Wednesday morning, Hadi Alodid, a 30-year-old refugee originally from Sudan, appeared briefly to face attempted murder and other charges following Monday's incident.

He was remanded in custody and the case was adjourned to July 8. The court heard Ogilvie had lost an eye in the attack. He remains in hospital "with serious injuries", according to police.

Footage of the stabbing -- which showed several people intervening, one wielding a hurling stick -- sparked widespread condemnation alongside anger. Despite pleas from authorities not to share the video, it went viral on social media.

Numerous accounts linked to so-called "patriots" shared the footage, urging people to "protest against mass immigration into their communities".

Northern Ireland police said three people had been arrested over the disorder, including 39-year-old and 42-year-old men who had been charged and were due to appear in court Wednesday. 

In Glasgow, there were also three arrests as two police officers and three members of the public were injured, Scotland's police force said. Worshippers at Glasgow's largest mosque were reportedly locked in as tensions flared.

As calls for more protests circulated Wednesday, Northern Ireland police chief Jon Boutcher said his force was looking to add a further 200 officers to the streets. 

Officers had to take a family that included a two-month-old baby to safety during Tuesday's violence, which he branded "a huge act of self-harm by mindless idiots", many of whom appeared to be young men.

'Bad faith actors'

Anna Turley, the chairwoman of Britain's ruling Labour party, said online platforms were "playing a role in driving" the unrest. She suggested X owner Elon Musk was one of the "bad faith actors" inflaming tensions.

Musk had retweeted a post by anti-immigration activist Stephen Yaxley-Lennon -- also known as Tommy Robinson -- adding: "Only by protesting REPEATEDLY and LOUDLY will there be any change!!".

He also retweeted a post by Rupert Lowe, leader of Restore Britain, a fringe hard-right party, saying "millions must go".

Musk "has a responsibility, everyone in public and civil life has a responsibility to call for calm and not to stoke grievance or hatred... that puts vulnerable people and our communities at risk," Turley said.

Britain's media watchdog Ofcom said it had written to online service providers about "the increased risk of their platforms being used to stir up hatred, provoke violence and commit other offences under UK law".

Alodid is a Sudanese refugee with a residence permit valid until 2028, according to the UK interior ministry.

Boutcher said he had arrived in the UK in 2023 via Paris and Dublin and "was not known" to police.

Immigration is a hot-button issue in Britain, and has helped fuel the rise of the hard-right Reform UK party, led by Nigel Farage.

The country has seen frequent anti-immigration protests in recent years, some turning violent.