Prodded by the most sweeping federal investigation in more than 20 years, Nevada is cracking down on organized crime's infiltration of this state's flourishing legal gambling industry.

In recent days the Nevada Gaming Commission has slapped a $100,000 fine, the largest in the state's history, against one corporation which allegedly permitted skimming operations at its horse-betting operations at two Las Vegas hotels. The entertainment director of another has been suspended on grounds of connections with the underworld.

And a source close to the gaming commission predicted that within 30 days the name of Chicago underworld figure Anthony (Tony) Spilotro would be added to the most exclusive Nevada listing - the "Black Book" of criminal figures barred from even entering a casino in this wide-open state.

Spilotro, described by federal authorities as the overseer of Chicago underworld interests in Las Vegas, has been a principal target of a Justice Department strike force investigation into penetration of Nevada gambling. An affidavit filed here in U.S. District Court reportedly said the government has reasonable cause to believe he is a hidden owner in the Stardust and Fremont hotel-casinos in Las Vegas.

Another target of the investigation is Allen Glick, a San Diego financier who owns Argent Corp., which operates the Stardust and the Fremont. Last week Argent agreed to pay a $100,000 fine for the sports betting skimming without admitting guilt. Two sportsbook employes face criminal charges.

Glick borrowed $62.7 million from the Teamster Central States Pension Fund to form Argent out of a company called Recrion, previously known as Parvin-Dohrman. The Parvin-Dohrman firm was barred several times from trading on the American Stock Exchange.

The strike force which is attempting to prove an intimate relationship between Spilotro and Argent, served 83 search warrants on June 19 and an undetermined number the same day in Chicago. They were issued on the basis of a still-sealed 150-page affidavit, which purports to describe organized crime infiltration into legalized gambling.

Spilotro, described as a lieutenant in the Chicago organized crime family once headed by the slain Sam (Momo) Giancana, was searched in the sweep. Federal agents said they found confidential reports to Glick about a former underworld asociate who was denied a license in Nevada.

Known as "Tony the Ant" because of his short and stocky (5 feet 4 inches) stature, Spilotro, 39, has been arrested a dozen times on charges ranging from murder to illegal gambling, but he has been convicted once, on a minor charge.

In one of his many trails, Spilotro was acquitted of murdering a suspected informer with an ice pick.

Prominent Las Vegas criminal attorney Oscar Goodman, who represents Glick and Spilotro, says he has "never seen anything that would demonstrate the nexus between the two men which the government alleges."

And Harry M. Reid, chairman of the Nevada Gaming Commission, says that his organization has no proof of any interlocking ownership in Argent involving Spilotro and would "suspend the corporation's gaming license in 30 seconds" if it did.

A crime that has especially interested the federal strike force is the unsolved murder of fromer Glick business associate Tamara Rand, who was shot to death in the kitchen of her fashionable San Diego home on Nov. 9, 1975, a week after the Giancana murder. Federal agents said that both were killed with .22 cal. bullets.

It was reported that according to an FBI affidavit, Rand was "brutally and savagely murdered," gangland fashion, as she was allegedly about to expose to law enforcement agencies evidence of Glick's illegal financial transactions.

Rand had loaned Glick $500,000, purportedly for a 5 percent share of Argent.

Whether or not the government, now presenting evidence in secret to a grand jury, can prove anything, it has clearly increased apprehension in Las Vegas to a level not seen since the mid-1950s, when then Gov. Charles Russell acknowledged that the state's gambling industry had been infiltrated by Murder Inc. and Mafia hood-lums from New York, Chicago, Miami, Detroit and St. Louis.

The attention given Nevada at that time - and the fear that the federal government would move in and out-law gambling - led to significant changes in the gaming commission laws barring hidden ownership and tough enforcement rules against cheating.

Hidden ownership is again an issue.

After a Detroit grand jury on Aug. 2 indicted Aladdin Hotel entertainment director James Tamer, an associate of Detroit underworld figures, for holding a hidden interest in the hotel, the gaming commission refused to grant him a license. Under Nevada law all casino executives must be licensed by the state and can be refused a license for criminal association.

There is considerable dispute in Nevada about whether the gaming commission is too diligent or not diligent enough. While attorney for Tamer and Spilotro talk of actions based on mere suspicion, others say that the commission usually acts against underlines and has taken no formal action against Argent despite repeated irregularities, which include the disappearance of $7 million in slot machine profits.

Recently the commission has moved to adopt tougher investigative rules, including a "no-knock" procedure approved last week allowing the Gaming Control Board (the Gaming Commission's enforcement arm) agents immediate access to all papers, books and records of a club and to nay area of a club involved in gambling.

Adoption of the rules over the opposition of the gambling industry was testimony, if any is needed, that the heat is on the Las Vegas.