Opposition leaders and mediators say they fear the army's troop buildup around rebel areas in southern Chiapas state could lead to war.

Roman Catholic Church mediators recognized last week by the government told a news conference late Monday that they would travel throughout the state, checking on the troop buildup.President Ernesto Zedillo met Monday in Mexico City with his defense minister and an undersecretary of the interior department, which oversees national security. There was no word from Zedillo's office on the purpose of the meeting.

The rebel Zapatista National Liberation Army began its revolt last New Year's Day, demanding improved living conditions and basic rights for Chiapas' impoverished Indians. More than 145 people were killed before a Jan. 12 cease-fire.

The guerilla war has threatened to reignite recently, posing a threat to Zedillo's new government. On Dec. 19, the rebels announced the deployment of thousands of fighters in Chiapas and blocked roads and briefly occupied towns in a show of force.

Since then, the Zapatistas haven't issued any more statements, but have dug huge ditches and chopped down trees to block roads into their territory in the Lacondon jungle.

The military, in response, has set up roadblocks and encampments around the rebel territory and deployed hundreds of troops throughout Chiapas.