A House subcommittee voted unanimously yesterday to subpoena the billionaire Hunt Brothers of Texas to testify next Tuesday about the silver-buying spree that caused the silver market to collapse last month.

The panel, which is headed by Rep. Benjamin Rosenthal (D-N.Y.), also ordered the Commodity Futures Trading Commission to turn over transcripts and tapes of all discussions about silver it has held since last August.

The series of subpoenas was issued by Rosenthal's government operations, consumer and monetary affairs subcommittee, which is running one of several federal investigations of silver.

Brothers Nelson Bunker and W. Herbert Hunt already have promised to testify voluntarily before a Senate Agriculture subcommittee next Friday. t

Neither the Hunts nor their lawyers could be reached for comment yesterday.

Staff members of Rosenthal's committee said they don't know whether the brothers will accept the House subpoenas and comply with the order to testify or try to avoid the appearance.

The orders to appear are expected to be served on the Hunts today or Thursday in Texas by U.S. marshals.

The Rosenthal subcommittee is looking mostly at how federal agencies handled the inflation and collapse of silver prices. From less than $10 an ounce last summer, silver prices soared to $50 on ounce in January, then began a plunge that bottomed out at $10.80 on March 27.

In several meetings with officials of the Commodity Futures Trading Commission last year, the Hunts repeatedly urged the federal regulators to keep hands off the market and insisted they were doing nothing illegal, CFTC officials have told Rosenthal's committee.

Rosenthal said he is concerned that the brothers "may have attempted to corner the silver markets." The Hunts are believed to have been the largest single buyer of silver during the metal's roller-coaster ride.

Last October the Hunts held 12,000 silver futures contracts, committing them to buy 60 million ounces of silver, according to a report by the New York Commodity Exchange.

At that time, silver futures were selling for $17 an ounce, making the Hunts holdings worth just over $1 billion. When the price of silver hit $50 an ounce, those contracts were worth more than $3 billion.