PARIS -- A man wearing a fake explosive vest and making threats was detained Friday outside the Iranian Consulate in Paris after police locked down the area, authorities said. His motive was unclear.

The incident came at a time of heightened tensions in the Middle East, and as Paris is on high security alert as it gears up to host the Summer Olympics in three months.

The suspect had been convicted for setting fire to the Iranian Embassy gates last year in what he called a protest against the Iranian government, according to the Paris prosecutor's office. The consulate and embassy are part of the same compound, in the ritzy 16th arrondissement of Paris and near the Seine River.

Iranian authorities did not comment publicly on what happened.

The man was spotted around 11 a.m. outside the consulate, and a witness told police he had a grenade and an explosives vest, according to a Paris police official. The official was speaking on condition of anonymity because he was not allowed to be publicly named under police policy.

Elite police forces and soldiers surrounded the area and barred traffic during an hours-long security intervention.

Iranian consulate in Paris

Inside the consulate, the man “allegedly made threats of violent acts,” but then left the building alone, the prosecutor's office said in a statement to The Associated Press.

Police then detained him, and found no weapons on him or his vehicle, the police official said. The prosecutor's office said the explosives vest turned out to be fake.

The suspect is in custody, and the Paris prosecutor's office opened an investigation into death threats. It said investigators are trying to determine the motive for the action.

Authorities did not name the suspect but said he was born in Iran in 1963.

He was known to authorities and received an eight-month suspended sentence by the Paris Criminal Court in October for setting car tires on fire at the gate of the Iranian Embassy in Paris in September 2023. He said it was a protest act against the Iranian government, according to the prosecutor's office.

As part of that sentence, the prosecutor’s statement said, the man was also banned from carrying a weapon and had a two-year ban on appearing in the 16th arrondissement. The sentence was pending because of the defendant’s appeal, it added.

Associated Press writers Thomas Adamson in Paris and Barbara Surk in Nice, France, contributed to this report.