In a last-ditch effort to avoid answering questions from federal investigators, the billionaire Hunts of Texas plan to go to court today to try to stop a wide-ranging government probe of their business dealings.

Facing an unprecedented federal inquiry into their jealously guarded family finances, the Hunts have asked a U.S. judge in Dallas to take the unusual step of halting an investigation by the Securities and Exchange Commission. Today the judge will hold a hearing on the Hunts' action.

The wealthy Texans are trying to head off what could be the most significant federal case brought against them, an investigation involving at least six members of the family. Prior federal investigations have accused various Hunts of trying to corner the market in soybeans and illegally bugging subordinates.

The latest federal investigation began last March, shortly after the price of silver collapsed when members of the Hunt family allegedly tried to corner the market.

A showdown in the year-long inquiry was originally expected this Wednesday, when the SEC had ordered Nelson Bunker Hunt to come to Washington for three days of questioning. William Herbert Hunt, Bunker's brother and partner in the silver business, has been subpoenaed to appear the following week.

Tying to head off their confrontation with the SEC, the Hunts sued the agency last Tuesday, accusing the SEC of violating their right to financial privacy and exceeding its jurisdiction. This afternoon, represented by attorneys from two Washington law firms, the Hunts are scheduled to go into federal court in Dallas to try to get a temporary injunction blocking the SEC probe or at least limiting its scope.

The Hunts want the court to prevent SEC attorneys from questioning them about their trading of silver and other commodities.

In an ironic defense of an agency whose powers they have previously tried to limit, the Hunt contend that only the Commodity Futures Trading Commission has authority to investigate their silver dealings. The CFTC accused the family of trying to corner the soybean market five years ago, and that agency, too, is investigating the silver market collapse.

But it is the SEC investigation the Hunts are concerned about. Pursuing leads gleaned from 25,000 pages of confidential Hunt business records, SEC attorneys have broadened their original investigation into an examination of the Hunts' dealings with four of Wall Street's biggest brokerage houses, several precious metals dealers and 30 banks in the United States, Canada, Germany, Luxembourg and Switzerland.

The SEC's handle for opening the door on the Hunts' usually secretive business is the agency's responsibility for protecting the integrity of the stock market, stock brokers and publicly owned banks.

The agency is investigating whether the Hunts' dealings with brokers and banks threatened those institutions' financial standing and indirectly the finances of other customers. The SEC also is studying whether the brokers and banks properly disclosed the impact of the Hunts' massive silver losses on the firms' own finances.

The SEC apparently also is pursuing accusations made by a former family employe, William Bledsoe. Testifying before congressional investigators last spring, Bledsoe charged the Hunts stole business secrets from major oil companies and manipulated the affairs of Great Western United, a publicly owned conglomerate in which the Hunts held controlling interest.

The bottom line of the complicated SEC probe is whether the Hunts broke any laws in the process of acquiring the world's biggest stash of silver. No one knows for sure how much silver the Hunts once had, but their holdings today amount to 63 million ounces, enough to supply the United States for six months.

For nearly a year the Hunts cooperated with SEC investigators, turning over thousands of pages of documents, said Thomas Whittaker, vice president of Hunt Energy Corp. in Dallas and spokesman for the family.

But suddenly this month they drew the line, refusing to produce additional records.

"We've given them 25,000 pages of documents everything they asked for, but this is just getting ridiculous," Whittaker said. "They're asking for things that have nothing whatsoever to do with the securities business."

Two weeks ago the Hunts forced the SEC to withdraw subpoenas for records from four banks. The SEC dropped the request after the Hunts complained in a federal lawsuit that the agency had violated provisions of the Right to Financial Privacy Act, a newly enacted federal law to protect confidentiality of personal financial information.

After winning that temporary victory (the SEC is preparing to resubmit the subpoenas in compliance with the law) the Hunts last Thursday filed a second lawsuit, hoping further to limit the SEC investigation.

Documents filed in the case show SEC lawyers have questioned several Hunt employes about the family's commodity trading, and Hunt attorneys have repeatedly objected to the questions about silver.

The SEC also is demanding that the Hunts turn over seismic logs from oil exploration and the financial records of Hunt employes, both of which could be used to corroborate charges made by Bledsoe. He claimed the Hunts did business in employes' names to hide the family's involvement. Bledsoe also accused the family-owned Penrod Drilling Co. of misusing oil exploration information it obtained while working for other companies.

The Hunts denounce Bledsoe as "a liar and a thief" who stole from his employer. Hunt Energy has sued Bledsoe, accusing him of diverting corporate funds to his use, conflict of interest and violating his legal duties to his employer. The Hunts turned their allegations over to a Texas grand jury which reportedly is considering indicting him on criminal charges.

The SEC investigation is not the only threat to the Hunts' financial privacy. Federal Reserve Board Chairman Paul A. Volcker last week expressed concern about the Hunts' continued hoarding of silver.

The Hunt interests' control of the estimated 63 million ounces of silver is worth about $800 million at today's prices. That is what is left of Hunt holdings once estimated, at a time of higher prices, to be worth $5 billion.

After the price of silver plunged from $50 an ounce to $10.80 a year ago last week, the Hunts had to sell much of their metal and take out a $1.1 billion bank loan to pay off their silver debts. Because the Federal Reserve at that time was trying to control inflation by prohibiting banks from lending money for speculative purposes, the Hunts had to get Volcker's permission for the loan.

Volcker was severely criticized in Congress for giving the Hunts a dispensation from his anti-inflation rules, but he said the loan was only a temporary measure to allow the Hunts to dispose of their silver in an orderly fashion.

But a year later, the Hunts have sold little if any of their silver, and they and Volcker are getting renewed heat from Rep. Henry S. Reuss (D-Wis.) chairman of the congressional Joint Economic Committee, and Benjamin S. Rosenthal (D-N.Y.), head of a House subcommittee that is still investigating the Hunts.

Telling Reuss and Rosenthal, "I share some of your concerns," Volcker said he has written the Hunts' banks reminding them that he approved the loan with the understanding it would allow the Hunts to sell their silver in "an orderly fashion."

The two congressmen complained that by tying up the $1.1 billion the Hunts "have hijacked from the nation's scarse supply of credit what might otherwise have gone into inflation-fighting loans for business investment."

Rosenthal and Reuss are demanding the Hunts sell their silver soon, but doing so would be a financial disaster for the family because of yet another government action -- the decision by the Reagan administration to sell the government's stockpile of 130 million ounces of silver.

If both the government's silver and the Hunt's goes on the market at once, the huge influx could force down prices.

Sale of silver from the stockpile requires congressional approval, and previous attempts have been blocked by members of Congress linked to the Hunts -- including Rep. Larry McDonald (D-Ga.) and Sen. Steve D. Symms (R-Idaho), both of whom have received campaign contributions from the Hunts.

The Hunts refuse to discuss their plans for disposing of the silver, saying any statements they make might be interpreted as an attempt to influence the price.

Silver trading sources speculate that the Hunts want to hold on to their metal in hope the price will go up. The Hunts refused to sell when prices climbed back to $23 an ounce a few months ago. Since then the price has dropped to $13 an ounce, making the Hunts' silver worth $630 million less than it was at $23.

In effect, the Hunts' silver has become a 63-million ounce white elephant, an asset they probably could not sell if they wanted to without taking a bath.

A Rosenthal subcommittee is still investigating the Hunts' tactics in acquiring the silver, and a task force representing the SEC, CFTC, Treasury and Federal Reserve is preparing a report.

Against that armada of federal agencies, the Hunts have lined up two Washington law firms -- Hogan & Hartson and Periot, Duerk, Carlson & Pinco, as well as their usual Texas attorneys from the firm of Shank, Irwin, Conant, Williamson & Grevelle.

Each of the lawyers represents members of the Hunt family. The issue of whether all the Hunts did business as one or acted independently has come up repeatedly in SEC questioning of Hunt associates.

The same issue was involved in the Hunt soybean case five years ago when the CFTC accused the family of violating limits on the amount any one speculator can buy. The Hunts insisted each member of the family was speculating on soybeans on his own, but a federal judge ruled the family holdings had to be counted as one.

In the current silver investigation, four other members of the family are involved with Bunker and Herbert, the brothers who nominally head the Hunt clan. The other four are brother Lamar, who owns the Kansas City Chiefs football team; Bunker's son Houston B. Hunt; Herbert's son Douglas H. Hunt, and Albert D. Huddleston, Bunker's son-in-law.