Soldiers wearing paper masks raced to cordon off the hilly countryside around Honey, a district in Puebla state 80 miles north of Mexico City, after the officer found the blue plastic barrels off a dirt trail, said the municipality's secretary, Juvencio Miranda.
Mexico's defense department said there were 70 containers and that they appeared to be part of the shipment of 96 drums of cyanide hijacked along with a chemical company truck May 10.
Twenty of the drums were found along with the abandoned truck a week later. State and local officials have given varying numbers for the drums found and some of the stolen cyanide could still be missing.
Water supplies to Honey were cut as a precaution against possible cyanide contamination, as experts at the scene tested the substance.
Honey is a mountainous district whose 11 villages hold 7,300 people. It is about 25 miles northwest of the spot where the truck was found and about 75 miles east of where it was stolen.
Miranda said when he visited the site, he saw between 60 and 64 blue, 220 pound drums of cyanide that had been dumped a few yards off a dirt road.
"You can see that they tossed them out and they are all turned over," he said, adding that at least two were open.
Mexican and U.S. officials were alarmed by the May 10 hijacking of a truck carrying the 96 drums of cyanide — roughly 10 tons.
Mexican authorities had mounted a large search for the cyanide and U.S. anti-terrorism officials had alerted Customs and state agencies to watch for the blue drums.
"The FBI is working with its Mexican counterparts to try and determine the nature of this crime and to determine where the missing cyanide is," Gordon Johndroe, spokesman for the U.S. Office of Homeland Security, said Tuesday.
There have been reports from New Zealand and Italy of cyanide threats against U.S. Embassies in the wake of the Sept. 11 terror attacks on New York and Washington.
The driver of the cyanide truck, Juan Carlos Alberto Lopez, was under guarded house arrest in Pachuca, Hidalgo's capital, about 55 miles north of Mexico City.
Lopez admitted to improperly leaving the main highway to take a shortcut, a secondary road toward the company that sells the cyanide, Degussa Mexico. He said he stopped — also against regulations — to help men in an apparently disabled car. He said those men pulled guns on him and stole his truck.
It was not the first incident involving the poison in Mexico.
About 220 pounds of sodium cyanide were found near a railroad track in northwestern Mexico on May 23. Officials said it apparently had fallen off of a train.
In late February, a truck loaded with 28 tons of cyanide crashed on an expressway east of Mexico City, forcing closure of the country's main east-west highway for 12 hours.
By Amparo Trejo