One person was killed and at least four others wounded when an explosive device detonated inside a residence in the southwestern Colombian province of Cauca, scene in recent weeks of fierce clashes between security forces and leftist rebels.

The blast occurred in El Plateado, a hamlet near the town of Argelia, according to media reports.

Residents have offered two conflicting accounts of the incident. While some say people inside the home were handling explosives, others insist the device was fired or lobbed into the residence from outside.

Intense fighting in Cauca between government forces and the Revolutionary Armed Forces of Colombia, or FARC, drove more than 2,800 indigenous and mestizo people from their homes in July.

Much of northern Cauca is the ancestral territory of the roughly 100,000 Nasa Indians, who six weeks ago declared themselves in "permanent resistance" with the aim of expelling the security forces and the guerrillas from their land.

Colombia's 1991 constitution guarantees autonomy for the nation's indigenous peoples and gives them the right to exercise control over their officially designated territories.

President Juan Manuel Santos traveled last week to La Maria, the main Nasa reserve, after the breakdown of talks between the Indians and members of his government on the indigenous residents' demands for real autonomy.

The president and the indigenous leaders agreed to establish working groups that are due to report back to Santos in two months. EFE