Lacandon Indians in the town of Nueva Palestina, wielding rifles and machetes, tried early Monday to evict neighbouring Indians from land they believe belongs to them.
The Chiapas state attorney general said four people were killed in the ensuing fight in the neighbouring town of Viejo Velasco.
"We have a count of four people dead up to now and another injured man in hospital," state attorney general Mariano Herran said on local radio.
The Lacandons, who experts say only number a few hundred, were once one of Latin America's most isolated indigenous groups, living in the thick jungle while the Spanish colonised the rest of the region.
They were largely ignored until the 20th century, when Indians from other areas of Chiapas began to encroach on the jungle region near the border with Guatemala.
Herran also said prisoners captured in the fighting had been released after negotiations.
Two human rights and environmental groups said they heard reports that up to 13 people from both sides were killed in the clash.
The violence follows years of feuding over land allotted to Lacandon Indians decades ago when the federal government confiscated parts of the remote jungle for logging and to create a biological reserve.
Chiapas, one of Mexico's poorest and most socially volatile states, is home to the Zapatista leftist rebel force that burst from jungles in 1994 in a brief but bloody uprising.

Copyright Reuters, 2006