Washington -- Federal agents said yesterday that they have made a "major dent'' in California's multibillion-dollar illegal methamphetamine industry, dismantling a criminal ring on both coasts that supplied some of the United States' largest meth labs with a chemical used to produce the drug.

Since Saturday, federal and local law enforcement agents have arrested eight of 10 kingpins of the loosely knit organization, which calls itself "the commission,'' U.S. officials said. They also arrested 140 lower- ranking participants in other cities around the country and seized more than 10 tons of pseudoephedrine and $8 million in profits.

Also arrested in connection with the operation were 36 Mexican- born methamphetamine traffickers operating high-volume meth labs throughout Southern California, federal agents said. Agents also seized 83 pounds of meth from the labs.

One of the leaders of the pseudoephedrine ring, Rabah El Haddad, was arrested in San Jose on Saturday, officials said. He and the other leaders have been charged with manufacturing methamphetamine for sale.

While federal agents say the organization they dismantled has competitors, they believe it was the largest and most sophisticated of its kind in the United States.

U.S. officials said the organization has been legally importing the chemical pseudoephedrine from China and India to New York, then diverting it to methamphetamine labs run by Mexican drug gangs throughout Southern California. Most of its members were born in the Middle East, and federal officials believe that tens of millions of dollars in proceeds have been routed to Syria, Israel, Jordan and Saudia Arabia.

"The impact is huge'' on the methamphetamine business in California, said Christy McCampbell, chief of the bureau of narcotic enforcement at the California Department of Justice. "That's not to say that it's going to stop methamphetamine manufacture in the state, but it will certainly slow it down, for a while anyway.'' The Bureau of Narcotics Enforcement raids an average of more than three methamphetamine labs a day in California. The agency estimates the state's annual output of the drug at more than 40 tons, worth about $400 million wholesale, or more than $1 billion on the street.

Pseudoephedrine is a key component of over-the-counter cold remedies, such as Sudafed, and can be legally imported by companies who register with the Drug Enforcement Administration. But it also can be combined with other chemicals to produce methamphetamine, a powerful stimulant also known as crank, speed and crystal.

Methemphetamine is produced in such large quantities in California that the Drug Enforcement Administration has labeled the state a "source nation'' of the drug.

DEA officials said that the trafficking reveals serious flaws in the agency's system for registering companies to import pseudoephedrine. They said that the traffickers created an intricate network of shell companies to move the chemical.

The enforcement operation marks the first time that federal agents have gone after pseudoephedrine traffickers. The use of pseudoephedrine in the meth trade has surged since 1994, when the DEA tightened controls on the importation and distribution of a similar chemical, ephedrine.