Two men have been charged with terror offences after police said they attempted to bomb a protest outside the New York City mayor's home in an attack allegedly inspired by the Islamic State group (IS).

The suspects, 18-year-old Emir Balat and 19-year-old Ibrahim Kayumi, allegedly told police that they aimed for the Saturday attack to be "even larger" than the Boston Marathon bombing in 2013 that left three dead.

New York police say the pair attempted to detonate two explosives outside Gracie Mansion, where Mayor Zohran Mamdani lives. Authorities found a third bomb in their car.

The incident happened during an anti-Islam protest. None of the explosives went off as intended.

Footage of the incident shows one of the suspects being detained just seconds after igniting one of the explosives, which did not detonate.

New York City Police Commissioner Jessica Tisch said the two suspect had admitted to being inspired by IS and had watched IS propaganda videos. The two did not have any previous criminal history, she said.

They are facing charges, including attempting to provide material support to IS and using a weapon of mass destruction.

"We were fortunate that the devices used this weekend did not cause the kind of harm that they were certainly capable of causing," Tisch said during a news conference on Monday. "But luck is never a strategy. Devices like these have the potential to cause devastating harm."

Tisch said one of the defendants, Balat, made several statements about IS while being transported to the police station, including saying: "If I didn't do it, someone else will come and do it".

Later, she said, Balat allegedly said he hoped the attack would be "even bigger than the Boston Marathon bombing, which he noted resulted in only three deaths".

That attack, which happened in 2013 as runners were crossing the finish line of the Boston Marathon, left three people dead and hundreds of runners and spectators injured, including many who lost limbs.

During their first court appearance on Monday, the two wore prison jumpsuits and a federal magistrate judge ordered them to be detained until their next court appearance on 8 April.

Following the hearing, Balat's lawyer said his client is a high school senior and a US citizen with no prior arrests and that he has "complicated stuff going on" in his personal life, the New York Times and Associated Press said.

The BBC has contacted both Balat and Kayumi's lawyers for comment.

According to court documents, both waived their constitutional rights to remain silent after their arrest.

Balat requested a piece of paper and wrote on it that he pledges allegiance to IS and called for death of nonbelievers or infidels, according to the criminal complaint obtained by the BBC.

Kayumi stated that he was affiliated with IS, watched IS propaganda on his phone and was partly inspired to carry out his actions that day by IS, court records say.

In a statement on Monday, Mamdani said that the two men charged "should be held fully accountable for their actions".

"We will continue to keep New Yorkers safe. We will not tolerate terrorism or violence in our city."

Tisch said the New York City Police Department remained vigilant in its counter-terrorism investigations and noted the heightened state of alert in the city and across the US due to the US-Israel war in Iran.

She thanked two of the officers who stepped forward "without hesitation and without regard for their own safety", after the devices were lit.

Tisch said an analysis of one of the devices showed it was made of triacetone triperoxide - "a dangerous and highly volatile homemade explosive". That material, she noted, has been used in other terror attacks and could have led to many deaths and injuries.

Tisch also said that officers had found a car in the city's Upper East Side that was tied to the two suspects. The NYPD used a robot that found another explosive device inside that was "consistent with the first two explosive devices".

In an earlier update, over the weekend, Tisch told reporters the protest outside the mayor's residence was organised by Jake Lang, a far-right influencer and pardoned 6 January rioter. That group was outnumbered by the counter-protest, which had over 100 participants.

As the two groups clashed, video from the scene confirmed by the BBC's media partner, CBS News, showed Balat throwing the first "ignited device", which extinguished itself after striking a barrier.

Balat then retrieved a second device from Kayumi, lit it, and started running before later dropping it, Tisch said. In the updates provided on Monday, Mamdani said both devices had been thrown.

The devices were reportedly made from glass bottles filled with explosive material and surrounded by fragmentation, or nuts and bolts, with a firework-type fuse.

"The FBI and NYPD confirmed the suspicious items to be improvised explosive devices (IEDs)", the FBI wrote on X.

"Additionally, the FBI Joint Terrorism Task Force (JTTF) will be conducting interviews, reviewing videos, collecting evidence, and chasing down all leads."

Police also arrested Ian McGuiness, 21, for allegedly using pepper spray on counter-protesters. He and three others were charged with disorderly conduct and obstruction. (BBC)

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