An “ultra-left anarchist group” has announced it was behind a power outage affecting 160,000 residences on the Côte d’Azur, occurring just hours before the Cannes Film Festival’s award ceremony.

Authorities in Grasse and Draguignan have initiated an investigation into potential sabotage following the online publication of a vague statement by the group.

In their unidentified communication, the group declared: “We disrupted the primary electrical substation serving the Cannes metropolitan region and severed the 225 kV line originating from Nice.”

They claimed the dramatic blackout was a deliberate attempt to cripple key infrastructure including research centres, start-ups, an aerospace factory, the local airport, and military and technological hubs.

Thousands of homes in the iconic French Riviera were left in darkness from around 10am on Saturday until the blackout was resolved at 4.30pm local time.

The suspected saboteurs wrote they targeted the region “on the eve of the Cannes Film Festival awards ceremony and gala evening” in what appeared to be a political statement, BFM TV reports.

Authorities have yet to verify the authenticity of the claims.

An initial arson attack struck an electrical substation in Tanneron, in the Var region, at around 2.45am on Saturday, weakening the power grid.

Hours later, a high-voltage pylon in Villeneuve-Loubet was discovered sawed through – further destabilising the network and triggering widespread outages.

The Draguignan prosecutor’s office has opened an investigation into the first attack, while a separate probe has been launched by prosecutors in Grasse into the second.

The investigation is ongoing.