The torture reports, and the fact that the Mexican army has sealed off the border area with Guatemala to keep journalists out and guerrillas and peasant sympathisers in, are threatening to make Mr Zedillo's get- tough policy backfire.
With the army in a position to act with impunity, there are widespread fears of human-rights abuses, even a scorched-earth policy of the kind used by Guatemala against guerrillas and peasant sympathisers in the 1980s.
The alleged torture and the news blackout have led to nation-wide protests, including a dramatic rally of 100,000 people in central Mexico City on Saturday night, and could prove to be a major embarrassment to US President Bill Clinton. The Clinton administration said at the weekend it backed Mr Zedillo's decision to try to end the Chiapas rebellion but with the clear provision, in the words of a State Department spokesman, that "at the same time, they must also respect their human rights".
The US assistant naval attach in Mexico City, Lieutenant-Colonel John Carroll, was turned back by troops on Saturday when he tried to enter the sealed-off zone to monitor the conduct of the army and heavily armed agents of the Prosecutor General's office.
Eight men and women detained in the eastern state of Veracruz last week on suspicion of belonging to the EZLN denied the allegation at their preliminary hearing and said they had been badly tortured. "They took me to a dark place and started hitting me again," said Hermelinda Garcia, a young Indian woman. "They asked me about Marcos [the guerrilla leader] and the EZLN and insisted I was from Chiapas. I kept telling them `no' but they kept hitting me in the head. Blindfolded, they led me to another place, where they stripped me naked and tortured me with electric shocks to every part of my body."
Such statements sparked Saturday night's march to Mexico City's historic main square, where many demonstrators wore black woollen balaclavas of the type worn by Marcos, carried gigantic painted portraits of the charismatic leader or chanted "Todos somos Marcos" (We are all Marcos).
One problem Mr Zedillo faces with his about-face on the rebellion - abandoning dialogue and ordering the arrest of the guerrilla leaders - is that Marcos has won a broad base of sympathy far beyond the Mayan Indian peasants of Chiapas who joined his rebellion. The name of his group was no coincidence. He sees himself as following in the footsteps of revolutionary hero Emiliano Zapata, with the aim not only of improving the lot of Indian peasants but of "national liberation" from Mexico's unbroken 65-year, one-party rule.
The Nicaraguan media reported yesterday that Marcos had come to that country in 1980, a year after the Sandinista revolution that overthrew the dictator Anastasio Somoza, along with thousands of young leftists and idealists. Villagers at San Juan de Rio Coco, 150 miles north of Managua, said he was known as "The Mexican" and popular for his habit of throwing birthday parties for Indian peasants.
As the army poured thousands of troops, tanks and jeeps towards the Guatemalan border to encircle the guerrillas in the new campaign, Marcos and his men appeared to have retreated deep into the jungle highlands known as the Blue Mountains. There were no further reports of clashes following Friday's EZLN ambush of an army patrol in which an army colonel was killed.
Marcos's peasant supporters in the historic town of San Cristobal de las Casas were relieved to learn at the weekend that he had apparently not been captured, that he had suspected an army assault and was vowing to wage a guerrilla war against the army. There had been widespread rumours that the army was holding him with the aim of parading him at a politically opportune moment. But a group of reporters said they had seen him on Thursday, shortly before Mr Zedillo announced his new policy and given the order for the guerrilla chief's detention. Marcos had already abandoned the group's headquarters in the village of Guadalupe Tepeyac - taken over by the army the following day - suspecting an army assault.
Despite Mr Zedillo's attempt to destroy Marcos's charisma by revealing him as a 37-year-old former philosophy professor, the pipe-smoking guerrilla chief appeared to have lost none of his charm or conviction. "They are threatening to annihilate us," he told the reporters. "but you can tell them surrender does not figure in our plans.
"We have been preparing because this is going to last a long time. They're pushing us towards long-term armed resistance. Whatever happens, we'll be in the mountains, resisting. "Furiously puffing on his pipe through a slit in his balaclava, he bade the reporters goodbye, walked towards the jungle and shouted back "Tell them we're going to win."
Confirming that the guerrilla chief had suspected a government clampdown, the daily Jornada published a letter from Marcos to the Interior Minister, Esteban Montezuma, dated 2 February, a week before Mr Zedillo's announcement. "You can pour at us all the soldiers you want but rest assured the conflict will spread throughout the country," he wrote. "Maybe annihilating us was one of the secret conditions for the US loans. But we will fight to the last man. From the mountains of south-eastern Mexico, Insurgent Subcomandante Marcos."
Most Mexican analysts believe that if the guerrilla leaders arenot captured within days, Mr Zedillo's attempt to harden his image will backfire, branding him with alleged human-rights violations without the counterweight of ending the rebellion.