Colombia's state ombudsman Friday urged authorities to protect civilians from violence between FARC rebels and renegade fighters deserting the force in protest at its peace accord with the government.

The FARC is preparing to demobilize under the accord but said its members had clashed with a breakaway group opposed to the agreement.

The unrest threatens to disrupt the FARC and government efforts to end their half-century-old conflict.

Ombudsman Carlos Alfonso Negret said various incidents had been reported in the south which posed a threat to civilians.

He said a woman was killed when regular FARC forces attacked a group led by a renegade commander.

The FARC earlier reported a clash last week in which it said one member of the breakaway group was killed.

The government warned in a statement that those involved in fighting at this stage in the peace process will not be covered by an amnesty included in the peace deal.