NICE, France, May 26, 2025 (BSS/AFP) - French authorities on Sunday blamed sabotage and ordered heightened security after a fire at an electricity sub-station in Nice caused the second major power blackout in two days along the Riviera.

The latest fire cut power to about 45,000 homes in western Nice for several hours, authorities said. Nice airport was briefly without electricity, the city's deputy mayor Gael Nofri told AFP.

A similar arson attack on a power substation on Saturday partially disrupted the final day of the Cannes film festival, forcing organisers to use backup generators to keep the event going.

Prosecutors said they had opened an investigation and were looking into a claim Sunday by two anarchist groups of "responsibility for the attack on electrical installations on the Cote d'Azur". The claim was posted on an alternative website.

"I vigorously condemn these criminal acts hitting our country," Nice mayor Christian Estrosi said on X.

"We are making images from our monitoring centre available to investigators and will strengthen the city's network at strategic electrical sites in coming days," he added.

"Until the perpetrators of these acts have been arrested, we will not ease up our attention anywhere," Estrosi told reporters.

Nice's chief prosecutor Damien Martinelli said studies had been carried out "to clarify the damage and the methods used to carry out the act" and that police were investigating "arson by an organised group".

Police said that tyre marks had been found near the Nice transformer and someone had broken into a room in the building.

An arson attack at a power substation and a bid to cut the legs of an electricity pylon near Cannes cut power to 160,000 homes in the region for five hours on Saturday.

The cut knocked out traffic lights and bank machines in Cannes, as well as threatening the finale to the film festival.

The festival "switched to an alternative electricity power supply" to keep the closing ceremony and award events going.

Firefighters battled for five hours to put out the flames at the sub-station, officials said.

In the attack on the high-voltage pylon, three of its four legs had been damaged, said prosecutors.