Danish police arrested a 33-year-old Muslim man in Copenhagen after he threatened on social media to behead members of the Swedish and Danish royal families.

The man, who has been described as being radicalised, made the threats on Facebook saying that he wanted to chop off the heads of the King of Sweden and the Queen of Denmark. His wife saw the remarks, and she reported him to the police, Expressen reports.

“This is the last warning to the Swedish police and border police. If I do not get an answer soon, I will with God’s will shut down both the state and the king, even if I then have to separate his head from his body,” the man wrote on social media.

The man’s wife told police that her husband, who lives in Copenhagen but also has Swedish residency, had experienced a deterioration in his mental state. She said he had made frequent trips to the Christiania area, a libertarian neighbourhood which is known for drug use, to smoke hashish.

UK Islamic State Sympathiser Encouraged Prince George Attack and ‘Poisoned Ice Cream’ https://t.co/Z3jpVPCu86 — Breitbart London (@BreitbartLondon) May 23, 2018

The 33-year-old is also said to have started hearing voices in his head and began writing several Facebook posts targetting figures such as anti-Islamist campaigner Rasmus Paludan. Mr Paludan became well known when riots erupted in Copenhagen following a protest led by him and his supporters earlier in the year.

This incident is not the first time a radical Islamic extremist has made threats against members of European royal families.

Last year in the UK, police arrested Islamic State supporter Husnain Rashid for encouraging others to kill Prince George, the young son of Prince William and an heir to the British throne.

Rashid, who published a pro-Islamic State magazine, allegedly created an “e-toolkit for terrorism” and called for Prince George’s school to be targetted. He was jailed for life in July 2018.