The Commodity Futures Trading Commission yesterday charged the Texas Hunt brothers and others with manipulating the silver market five years ago in the biggest commodities trading scandal in history.

The civil complaint asks that Nelson Bunker Hunt and William Herbert Hunt be barred permanently from using all commodity futures markets and fined $100,000 for each violation of federal law. It is not clear from the complaint how many separate violations the Hunts were charged with.

The Hunts and the others have 20 days to respond to the CFTC complaint in what is, by far, the biggest and most complex case ever tackled by the 11-year-old agency. The CFTC spent five years investigating the rise and fall of silver prices in 1979 and 1980 before filing the complaint against the Hunts.

Walter Roach, general counsel of Hunt Energy Inc., said the Hunt brothers had not seen the complaint but, based on the commission news release, "the thrust of those allegations are baseless. The Hunts will defend themselves and will be ultimately vindicated."

According to the CFTC, the Hunts and their associates managed to drive the price of silver from about $11 an ounce to $50 an ounce in less than five months, before their scheme foundered and the price of silver collapsed.

When the price plunged, the Hunts and the other silver speculators lost billions of dollars and were unable to pay their debts to several of the nation's biggest brokerage firms. The unraveling of the Hunts' scheme threatened to trigger a major financial panic until major banks, with Federal Reserve approval, made a controversial billion-dollar loan to protect the Hunts' creditors.

The CFTC alleged that the Hunts conspired with a number of other wealthy investors to raise the price of silver artificially during a seven-month period beginning in September 1979.

The agency's enforcement staff said the Hunts and the others systematically bought up silver all over the world in an effort to create shortages and jack up the price. Participants in the plan besides the Hunts allegedly included Brazilian investor Naji Robert Nahas, New York silver trader Norton Waltuch, a Swiss investment firm and a Bermuda corporation.

Starting in May 1979, the speculators worked together to buy large amounts of silver and silver futures contracts, the CFTC said. By July of that year, the complaint said, the conspirators had established positions in the silver futures contracts on the New York Commodity Exchange and the Chicago Board of Trade that were designed to enable them to control much of the available silver in the world, squeezing out other traders and driving the price higher each day.

Until they began to execute the plan in September, the Hunts had followed the normal behavior of most futures traders, buying contracts for future delivery of silver and then settling the deals in cash when the contracts matured, the complaint said.

On Sept. 1, 1979, the Hunts and others began to demand silver when their contracts expired, forcing holders of the contracts to buy silver bullion, which was in short supply because the Hunts had bought so much.

According to the CFTC, the Hunts were in a position to demand 206 million ounces of the metal between Sept. 1 and the next May. That represented nearly half the world's annual silver production and more than all the silver used in the United States for industrial purposes.

Every time the Hunts and others demanded delivery on their futures contracts, the amount of silver available to satisfy contracts declined and the price of the metal rose.

The complaint said that when the Chicago and New York exchanges took steps in late October to limit the attempt to squeeze the market, the Hunts misled them about their intentions. In January, when the exchanges set a limit on the number of new contracts that could be acquired, the Hunts and their allies began to establish accounts in the other names, the complaint alleges.

Finally, in late January, the exchanges took extreme actions to force the Hunts and others holding silver futures contracts to sell off their positions. When that happened, the price of silver began to fall. The Hunts have alleged that the exchanges took the actions to protect their own members from high prices, not to protect the futures markets themselves.

CFTC sources said the agency is still investigating the action of the exchanges and the charges made by the Hunts.

To try to keep the price of silver from declining once it had peaked, the Hunts and their allies continued to purchase silver throughout February and most of March, when prices were falling daily. The CFTC complaint said Nahus and Nelson Bunker Hunt criss-crossed the world trying to boost the silver price and moving silver and cash around to keep their brokerage accounts current.

Soon, however, even the billionaire brothers ran out of money, and on March 26, 1980, notified their creditors they could not pay their debts.