SAN CRISTOBAL DE LAS CASAS, MEXICO, JAN. 3 -- Battles raged today throughout southern Chiapas state in a three-day-old peasant uprising, and the Mexican military acknowledged tonight that an army base outside this colonial city is under heavy, sustained attack by rebel forces.

The military also said guerrillas of the Zapatista National Liberation Army, composed mainly of Indian peasants, was fighting with army troops for control of the eastern town of Ocosingo, which had been under rebel control through the weekend.

Complaining of social injustices and vast disparities between rich and poor in this impoverished south Mexican state, the Zapatista army, a previously unknown organization, seized at least four towns and a half-dozen villages near the Guatemalan border during a surprise revolt that began shortly after midnight Saturday.

Despite continued rebel control of at least two large towns and several villages, the government of President Carlos Salinas de Gortari said it regarded the Zapatistas as a small group of provocateurs and "delinquents" who are trying to draw the armed forces into prolonged warfare.

In a statement today, Salinas appeared to acknowledge the guerrillas' main complaint that greater efforts need to be made to reduce the gap between rich and poor in the state. But he called on the Zapatistas to seek peaceful solutions to their problems, noting that "acts of violence only delay the real solution."

As of today, the guerrillas maintained control of the eastern towns of Alamirano and Las Margaritas, as well as a half-dozen villages in southern Chiapas. Heavy fighting was reported today in and around Ocosingo, a city of 120,000, where, according to unconfirmed reports, as many as 50 rebels have been killed during two days of fighting.

The death toll among civilians, police, rebels and army troops appeared to have exceeded 100 as of tonight, but the military said it was unable to confirm the number of rebel casualties. Telephone communications have been cut with all municipalities under rebel control.

State Secretary General Rafael Gonzalez said in a television interview today that former governor Absalon Castellanos, a retired army general, had been abducted by guerrillas from his ranch outside the town of Las Margaritas. Gonzalez acknowledged that Las Margaritas and Altamirano remained under rebel control.

In a major jolt to the Salinas government, rebels early Saturday captured San Cristobal de las Casas, the second-largest city in Chiapas, but withdrew early Sunday. Today, scores of government troops patrolled the city center and blocked hundreds of European and American tourists from entering a popular central shopping plaza, the scene of heavy destruction when it was seized by rebel forces over the weekend.

Less than 10 miles east of San Cristobal, guerrillas continued to attack an army battalion headquarters. Military helicopter gunships flew over the scene this morning at a rate of one every four minutes, but only sporadic gunfire could be heard from the city. The army said two soldiers and 27 guerrillas were killed and nine soldiers wounded during a battle that started at 10 p.m. Sunday and continued throughout today.

About two miles from the army headquarters, guerrillas attacked a regional prison on Sunday and freed an estimated 180 prisoners.

Church and government officials said they were trying to negotiate a solution to the conflict, with possible mediation by San Cristobal Bishop Samuel Ruiz, who reportedly maintains close contact with local indigenous peoples. Last October, the Catholic Church threatened to remove Ruiz from his diocese here because of his alleged advocation of "liberation theology" and his support of radical indigenous causes.

An aide to Ruiz, Vicar General Gonzalo Ituarte, said in an interview today that church officials are open to serving as mediators but acknowledged "it will be very difficult." He indicated that the Indians' decision to take up arms showed they had given up hope of non-violent solutions. Asked if he expected the conflict to last a long time, he said: "We hope no, but we fear it will."

Chief among the rebels' stated grievances is that the North American Free Trade Agreement, which took effect on New Year's Day, will become yet another instrument for powerful American capitalists to exploit the region, drain it of natural resources and force Indians off land they have farmed for centuries.

Observers here said the guerrilla attack should have been anything but a surprise to Salinas because Indians throughout Chiapas have been airing their complaints and concerns openly for decades.

"We can see from our own files over the past 10 years that almost on a daily basis they have been complaining about injustices against poor indigenous peoples. . . . But nobody listened," said Concepcion Villafuerte, editor of the newspaper El Tiempo, which has closely followed the plight of southern Mexico's large Indian population.

The Mexico City magazine Proceso reported last September that armed indigenous groups were training in Chiapas, but the state government immediately denied the report. "There are no guerrillas in the state," Chiapas Attorney General Joaquin Armendariz told reporters in November. "This alarm is definitely false and comes from people who are trying to discredit the government and foment unrest among the citizenry."

"Either the government didn't know or didn't want to know" that the Indians were mobilizing militarily, Villafuerte said.

Ituarte said that as far back as 1960, Bishop Ruiz had warned of the "gigantic disequilibrium between the rich and poor in Chiapas" and had condemned the extreme poverty and lack of economic resources available to the state's indigenous population.

"For 34 years, he talked to all of the governors of the state and all of the presidents in Mexico City" about the Indians' grievances, Ituarte said, but still large income disparities remained. Chiapas and neighboring Oaxaca, both home to large Indian populations, are the two poorest states in Mexico. "We are modernizing in the north and moving closer to the United States and Canada without giving justice to the poor people of the south. No mere declaration or free-trade treaty is going to solve the problem."

PEOPLE AND LOCATION:

Most of its people are at least part Indian. Potentially rich in natural resources, including natural gas and petroleum, Chiapas remains one of Mexico's most impoverished states. It is largely undeveloped, with cattle-raising and the cultivation of coffee, cacao and rubber the base of its economy.

GRIEVANCES:

Lacandon and other Indian peoples in Chiapas state have long been feuding with state and federal authorities, often over land. They complain that lumberers, land sharks and cattle ranches are encroaching on their native habitat, the rain forest, and the government is doing little to help. The government says it has been trying to help but also says the region's troubles are rooted in its history and difficult to resolve.

THE REBELS:

The rebels claim their numbers run into the thousands; the government says there are only a couple hundred. The rebels appeared well-coordinated and witnesses to their attacks said they seemed well-trained. Rebel leaders say their force was trained in the heavily jungled Lacandon mountains and deny rumors of help or connection with outside guerrilla movements. Witnesses say the rebels have weapons including automatic rifles and hand grenades. Many wore military fatigues and other battle uniforms, some of them new.

SOURCE: Associated Press