Two scooters for the courier service were set alight in the arson attack and death threats against the far-right mayor were tagged on the building, according to Bruno Bilde, deputy mayor in the town of Hénin-Beaumont, L'Express reported.
Vandals also sprayed graffiti inside the building, with tags including “Charlie is dead”, a reference to January’s terrorist attack against Charlie Hebdo, “Ben Laden”, “Die Briois” and “Die Brice”, thought to be a reference to mayor Steeve Briois and Laurent Brice, an employee at the Town Hall.
A ground-floor window was also smashed in the break-in.
The alarm was raised by two employees at the Town Hall when they saw thick black smoke.
Fire fighters arrived at the scene around 6am on Wednesday by which time the fire had been extinguished, emergency services told Express.
The arson attempt comes as National Front leader Marine Le Pen is set to hold a meeting in the town on Wednesday evening.
The incident comes two days before the second round of France’s departmental elections in which the far-right party has once again achieved historic results.
In a key test ahead of the presidential vote, Nicolas Sarkozy's centre-right alliance took first place with 28.7 percent of the vote, while the National Front came second with 25.2 percent.
The Socialists trailed in third with an estimated 22 percent, the latest haemorrhage of support for the party since Hollande, who has failed to address double-digit unemployment in the eurozone's second-largest economy, took charge in 2012.
Hénin-Beaumont Town Hall. Photo: Kotembal/Wikicommons