SAN CRISTOBAL DE LAS CASAS, Mexico (AP) _ Government soldiers pursued guerrilla leaders into the jungles of southern Mexico on Sunday, sending dozens of peasants fleeing. No new violence was reported.

The government says it is trying to avoid confrontations, and Guatemala promised to assist the Mexican army by preventing rebels from crossing the border.

``In no way is this being treated like a war,'' the Mexican Interior Ministry said in a statement.

The government has portrayed its troop movements as a police effort to enforce an arrest warrant, but military roadblocks prevented the entrance of medical supplies and food to impoverished Indian villages.

Human rights groups expressed concern that the army was planning a major offensive against the rebel Zapatista National Liberation Army.

``We think that the army is preparing an offensive, that the soldiers are circling the Zapatistas with the intent of eliminating them,'' said Roger Maldenado of the human rights group Conpaz.

Transport trucks and light armored vehicles begin rumbling into rebel territory in the southern state of Chiapas after President Ernesto Zedillo announced Thursday that he had ordered the arrest of top rebel leaders, including the ski-masked Zapatista spokesman, Subcomandante Marcos.

Zedillo said authorities had discovered that the Zapatistas ``were preparing new acts of violence and terrorism in the state and other parts of the republic.''

One military officer was killed by an unidentified gunman after the army began its advance on Thursday.

On Sunday, in the isolated village of Nueva Providencia, helicopters landed and soldiers patrolled the brush that has been Zapatista territory for most of the past year.

Some peasants in the village, about 90 miles east of San Cristobal, said they decided to stay.

``If the army is going to kill us, better that they kill us in our own homes.'' said Hernando Vazquez Hernandez.

The Zapatistas began fighting on Jan. 1, 1994, demanding rights and services for the region's impoverished Indians. More than 145 people were killed before a cease-fire was declared 12 days later.

The guns have been silent since then, but peace talks have faltered and Zedillo has come under increasing pressure by the military and investors to resolve the conflict, which has been blamed in part for the nation's financial crisis.

Since Zedillo's announcement Thursday, authorities have raided at least three houses, seized an assortment of weapons and arrested about 30 people, including three suspected rebel leaders.

By Sunday, the army had formed a circle around the Lacandon Jungle region where the Zapatistas have long had their headquarters.

The International Red Cross announced during the weekend that it was withdrawing from the former rebel stronghold of Guadalupe Tepeyac because soldiers' takeover of the hospital compromised the group's neutrality.

The Interior Ministry insists human rights are being respected but has allowed neither rights activists nor journalists access to the area.

There has been no communication from the Zapatistas since Zedillo identified Marcos as the son of a well-to-do businessman from the northern city of Tampico and sent troops to arrest him.