At least eight people posed in Ku Klux Klan outfits outside an Islamic prayer centre near Belfast at the weekend, in an incident that is being investigated as a hate crime.

The hooded individuals were photographed with their arms aloft and their fists clenched outside the building in Newtownards, County Down on Sunday evening. At least two were holding a wooden cross. The centre was subject to an apparent Islamophobic attack last year when a severed pig’s head was left by the entrance.

George Hamilton, the chief constable of the Police Service of Northern Ireland, described the incident as “disgusting” and confirmed his officers would be investigating it as a hate crime. “There’s no place for it anywhere in Northern Ireland and we will investigate this, we will gather evidence and we will report that evidence to the public prosecution service,” he said on local radio.

The incident has been widely condemned by political and religious leaders. Dr Raied Al-Wazzan, of the Islamic Centre in Belfast, said: “I understand it is Halloween, people are dressed in costume, but to go there specifically wearing that costume in front of an Islamic centre is not acceptable.”

Speaking to BBC Radio Ulster’s Nolan show he added: “Unfortunately this is not the first incident that has happened around Newtownards. This is the second time [the centre] has been targeted.”

Iman Atta, the director of Tell Mama, a group that campaigns against Islamophobia, said: “Standing outside a mosque with KKK hoods sends a message that Muslims are not only unwelcome, but that they should beware. The police need to find these individuals and haul them into court to send a message that such hate will not be accepted.”

Kellie Armstrong, an Alliance party Stormont assembly member, urged the police to review CCTV evidence from local bars where the group were believed to be drinking before putting on their masks.

She said: “Everyone knows exactly what the KKK stands for. The KKK represents a brand of hatred not wanted or welcome in the area. This group did not simply dress up for Halloween, rather they deliberately posed outside the prayer house in Newtownards.

“This is a clear demonstration of aggression and bullying towards one particular religion and that is a hate crime.”

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Peter Weir, a DUP assembly member for the area that covers Newtownards, said: “The Ku Klux Klan is a deeply repugnant racist organisation and anyone happy to associate themselves with such a vile body is clearly a moron. That such a large group of people took the time and the effort to get their costumes completely correct, and above all the fact that they chose to pose outside the Islamic prayer centre in Newtownards, takes this episode of stupidity to a more sinister connotation.”

The PSNI confirmed it had received reports at about 5pm on Sunday of a group of people dressed as KKK members around Greenwell Street in Newtownards.

Insp Richard Murray said: “Hate crime, in all its forms, is totally unacceptable. It is the responsibility of each and every one of us to ensure that we live in a society where diversity is respected. Our inquiries are ongoing, and we are treating this as a hate incident at this time.”