Mexican Army Seals Off Highways During Search for Rebel Indians : Unrest: Action concerns human rights groups. In wake of violence, government sends supplies to the Chiapas region.

Mexican soldiers searching for Indian rebels sealed off highways out of a southern region’s main town Thursday, stirring concern among rights groups looking into reports of abuse by troops.

Late in the day, the army also apparently launched a new offensive against the guerrillas. Four airplanes fired rockets near the rural town of Cerro Huitepec, three miles southwest of this regional center. There were no immediate reports of injuries or damage.

The government, however, took steps to build support in Chiapas state, a poor, predominantly Mayan region. Officials said 20 tons of rice, beans, powdered milk and other food was being flown to the state.

The federal government also promised to strengthen its public works programs that build roads, schools and hospitals in the area. Rebels said they began the uprising Jan. 1 to highlight the plight of poor Indians in Chiapas.

The presidents of El Salvador, Guatemala and Nicaragua and the president-elect of Honduras were to arrive today in Mexico City to discuss the crisis and show their solidarity with Mexican President Carlos Salinas de Gortari.

The insurrection has rattled Central Americans in countries newly emerging from years of civil war.

Six days after the uprising broke out, rebels were still active in some remote areas of Chiapas, a lush mountainous region bordering Guatemala and the Pacific, Interior Ministry spokesman Eloy Cantu Segovia reported.

The village of Chanal east of San Cristobal de las Casas was reported to be in rebel hands by seven villagers who fled on foot over the mountains Wednesday. There had been conflicting reports on whether Chanal was recaptured by the army this week.

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One of the seven, Marcelino Gomez Lopez, told El Tiempo newspaper in San Cristobal on Thursday that the rebels were not allowing villagers to leave. The rebels shot and killed a schoolteacher who tried to escape, Gomez Lopez said.

The military said 105 people had been killed since the uprising began with coordinated attacks on towns in Chiapas, Mexico’s southernmost state.

The rebels from the previously unknown Zapatista National Liberation Army said they were fighting for socialism and to improve the lot of Indians who lack potable water, food, education and housing.

On Thursday, soldiers sealed off southbound highways out of San Cristobal, the region’s main town. Helicopters hovered overhead.

Most of the fighting has been south and east of San Cristobal.

Heavily armed troops guarded the main square in the colonial town of 80,000 people, about 450 miles southeast of Mexico City.

An Associated Press correspondent reported no untoward events Thursday along the one highway open into San Cristobal from Tuxtla Gutierrez.

San Cristobal and Tuxtla Gutierrez, the capital of Chiapas, were the only places accessible in the region to reporters and independent human rights observers, who expressed concern about the army’s move.

“If security reasons make it necessary to seal off areas, it should be explained and should be temporary. Otherwise it raises concerns about . . . violations,” said Juan Mendez, executive director of Human Rights Watch-Americas, an organization monitoring rights violations in Latin America.

Salinas sent his top human rights official to the battle zones to investigate possible army abuses. Jorge Madrazo, chief of the government-run National Human Rights Commission, arranged Thursday to start taking complaints.

“I think we would be calling on the Mexican government to allow both the press and an impartial human rights investigation to take place,” Mendez said by phone from Washington.

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He said his group was concerned particularly about two incidents: the apparent execution-style killings of rebels in Ocosingo, site of the fiercest fighting, and the deaths of about 17 people whose bodies bore battered faces and bullet holes in the head.

The Peasant and Agricultural Workers Center, an organization independent of the government, reported meanwhile that the army arrested five of its leaders bound for a meeting Wednesday with government officials in Tuxtla Gutierrez.

It said in a news release that their whereabouts were unknown and expressed concern for their safety.

The naked bodies of three men and a young girl killed while driving out of San Cristobal remained unclaimed in a chapel in the general cemetery.

The local newspaper El Tiempo said it knew of three survivors of the van shooting incident, a focal point of concern by rights groups. Its reporters said at least two of the three were unconscious, that all were civilians and were in a military hospital.

In Mexico City, the daily El Universal said a message purportedly sent by the rebels said they were organizing an urban front to fight the idle rich throughout Mexico. The note was left in a movie theater bathroom, it said.