A viable device was thrown through the window of the Belfast Islamic Centre during an attack on Friday night, police have said.

People from the centre were praying inside the building on University Road when the attack was reported at about 22:10 BST.

The incident sparked a security alert and the building was evacuated.

Police said a 34-year-old man was arrested under the Terrorism Act but added that a motive for the attack has not yet been established.

“Ammunition Technical Officers attended and examined the object which was determined as viable and has since been removed for forensic examination,” said ACC Anthony McNally from the Police Service of Northern Ireland.

“Detectives from Serious Crime Branch are currently working at pace and are exploring a number of potential motivating factors including the possibility that this is a hate crime.”

Kashif Akram from the Belfast Islamic Centre told BBC News NI a window had been broken and device thrown inside, while up to 30 people were upstairs praying.

He said the attack has caused alarm among the Muslim community.

“There was a lot of commotion outside, that’s when people realised from upstairs that something was happening outside. Thankfully nobody was hurt.”

Mr Akram added: “They were very angry, very upset, they were here to do their prayers, minding their own business.”

He praised the fast response of the security workers at the building, and the police.

“Unfortunately, the place was cordoned off last night and we couldn’t continue with our congregational prayers last night or this morning.

“Thankfully, the building is back in operation since six this morning, everything has been cleared and we’ll be fully functional today.”

Raied Al-Wazzan, a former treasurer of the Belfast Islamic Centre, said the centre and some neighbouring properties had been evacuated when he arrived.

Having spoken to security at the centre, he said he understood someone had tried to enter the building via the front door but was turned away.

“He was trying to get in and security stopped him. He was carrying a bag on his back and… also carrying a brick.”

Mr Al-Wazzan said the person then walked to the side of the building and smashed a ground-floor window with a brick.

At this point, it is reported that a passer-by interrupted the incident.

“He tried to protect the centre actually and we thank that gentleman and we hope we could find him and thank him in person.”

Northern Ireland Secretary Hilary Benn posted on X that he was “deeply concerned by the shameful attack on the Belfast Islamic Centre”.

“Hatred of this sort has no place in Northern Ireland,” he posted.

SDLP leader and MP for the area, Claire Hanna, said she was “appalled” by the attack.

“I am hugely relieved that no one was seriously injured, but this was a frightening and disturbing experience for the centre’s users and for all of us who value a peaceful and shared society.

“Belfast is an open and welcoming city. No one should ever feel unsafe in their place of worship.”

The Ulster Unionist leader Mike Nesbitt said the attack was “wrong, period”.

“People of that faith are hospital surgeons and consultants, governors of our schools, contributing members of our society – unlike the racists who carry out such attacks,” he added.

Alliance assembly member Paula Bradshaw said: “This is just the latest example of an attack motivated by hate which does not reflect the diversity of south Belfast in 2025,” she said.

“This attack was again designed to cause fear among people inside the centre, who were at prayer at the time.”

Sinn Féin’s Deirdre Hargey condemned what she called a “sinister” attack and added her “thoughts are with everyone affected”.

“Acts like these, fuelled by hate, spread fear and division, and target people who have come to our communities to build a life and call this place home.”

Green Party councillor Áine Groogan said it was “another reminder of the very real danger faced by our Islamic community”.

“The recent rise in racist hate and violence on our streets is a shameful stain on our society,” she added.

The Police Service of Northern Ireland (PSNI) said the detained man remains in custody.