Police in the United Kingdom said on Thursday that they were investigating a "hate-motivated criminal offense" after a model of a mosque was placed on top of a loyalist bonfire in Northern Ireland.

The mosque replica, which was visible atop a pyre in the town of Moygashel in County Tyrone alongside with the Arabic words "Islamic fascism," has been widely condemned by political parties, religious leaders and human rights groups.

The Police Service of Northern Ireland (PSNI) said a 56-year-old man arrested earlier on Thursday remained in custody while they continued to "assess the situation."

Signs reading "Secure our borders" and "End the threat of radical Islam" have also been placed on the pyre, which is due to be set alight on Friday night to mark the "Eleventh Night" on July 11, ahead of further celebrations and parades on "The Twelfth" – July 12.Northern Ireland: What are the bonfires all about?

For the loyalist community in Northern Ireland, the bonfires commemorate the Glorious Revolution of 1688, when the Protestant King William III of Orange deposed the Catholic King James II of England, and the subsequent Protestant victory at the Battle of the Boyne in what is now the Republic of Ireland in 1690.