Corsican separatists, who claimed responsibility for dozens of attacks last year, on Tuesday warned of fresh violence as France's interior minister toured the crime-prone island.
"We will take up arms again so that France recognizes our national rights," the Corsican National Liberation Front (FNLC) said in a statement, denouncing Paris for supporting a centralized republic.
But after vowing "zero tolerance" for mafia groups, Interior Minister Manuel Valls said: "We will not let ourselves be browbeaten by threats."
The FNLC, which was set up in 1976, and various other factions intent on self-rule have staged hundreds of attacks in Corsica. They have also been blamed for armed robberies and extortion through so-called revolutionary taxes.
The French Mediterranean island of 310,000 people is popular with tourists for its spectacular beauty, but it has also been hit by a serious crime wave.
There have been 11 murders on the island this year so far and 30 since the start of last year, leaving Corsica with the unwelcome status of having the highest murder rate in Europe.
Police believe most of the killings were linked to feuds between rival criminal gangs with ties to sections of the Corsican nationalist movement.