French police prevented an apparent bomb attack outside a US bank in Paris on Saturday when they arrested a man about to set off a homemade explosive device, officials and sources close to the case said.

The incident occurred at about 3.30am (0230 GMT) in front of a Bank of America building in the city’s 8th arrondissement, a couple of streets away from the Champs-Élysées.

Police grabbed the man just after he had placed a device that held five litres of liquid, believed to be fuel, and an ignition system, one of the sources said.

The ignition component had 650g (23 ounces) of explosive powder inside it, according to an initial assessment. The device was taken to the Paris police’s forensics lab for full analysis.

France’s counterterrorism prosecutor’s office said it had immediately taken over the investigation and confirmed the suspect was in police custody.

It said the investigation was looking into “attempted damage by fire or other dangerous means in connection with a terrorist undertaking” and a “terrorist criminal conspiracy”.

The Paris judicial police and France’s domestic intelligence service, the General Directorate for Internal Security, are also involved in the investigation, according to the counterterrorism prosecutor’s office.

France’s interior minister, Laurent Nuñez, hailed the officers’ speedy action in a post on X, referencing “the current international situation”, in which European countries have increased domestic security concerns because of the war in the Middle East.

He said vigilance in France “remains more than ever at a high level”.