BASTIA, France (AFP) -- A house in Corsica was badly damaged by a bomb blast late Saturday, local police said.

An enquiry has been launched into the blast at the house, a holiday home which was not occupied at the time.

French Interior Minister Nicolas Sarkozy warned Corsican separatists on Thursday that he will crack down on their "mafia-like" tactics in a bid to starve financing of their three-decades-long campaign of violence.

The message, delivered to Corsican politicians during a visit to the Mediterranean island, was met with open defiance from the groups fighting for self-rule.

Attacks have surged since July, when a referendum sponsored by the French government that offered limited autonomy in exchange for an end to the violence was narrowly defeated by Corsica's wary 260,000 inhabitants.