Police detained a man who threw what officers said were "ignited devices" near far-right protesters demonstrating at the residence of New York's mayor Saturday, AFP correspondents saw.

NYPD Commissioner Jessica Tisch said the devices contained nuts, bolts, and screws as well as a fuse — but it was not yet clear if they were functional improvised explosive devices, or hoax imitations.

There was no indication the incident was related to the ongoing hostilities in Iran, she added. Far-right influencer Jake Lang was demonstrating against alleged "Islamification" and calling for an end to "public Muslim prayer" in New York in front of Gracie Mansion, the residence of mayor Zohran Mamdani, who is Muslim.

His protest drew around 20 people, police said, while counter protesters numbered approximately 125. A man wearing a dark hooded sweatshirt and beige cargo pants was handed a device wrapped in tape and billowing smoke by a fellow activist. He dropped it near a line of police before vaulting a crash barrier.

The man also threw a similar device near Lang's group of protesters. "Witnesses reported seeing flames and smoke as it travelled through the air before it struck a barrier a few feet from police officers," Ms. Tisch told a briefing, naming the suspect as Amir Balat, 18.