Several hundred German citizens who say they have been taken by a classic desert land fraud in Nevada appear to be out of luck, according to German authorities who have tried to intervene with state officials there.

However, state officials have reopened an investigation into the Las Vegas firm involved after it was learned that the company was still advertising land sales in Europe.

In what appears to be a "Catch-22" situation, Nevada officials told a German government representative last week that the state did not have jurisdiction over the land sales involved, which occured for the most part in the 1970 and 1971.

Sales by Preferred Equities Corp. of Las Vegas to about 700 Germans through a complex investment fund arrangement "are exempt from our land sales act because the seller was registered with the federal Department of Housing and Urban Development before our act became law," said Nevada Land Division official Angus MacLeod in a telephone interview.

MacLeod said that he met with the German representative, Heinz Pallasch of the German consulate in San Francisco, "and I told him it was out of our jurisdiction."

But in Washington, HUD officials said that they were prevented from taking action because the alleged violations occured so long ago. "We have a five-year statute of limitations on criminal fraud," on official said.

Last week, however, deputy state Attorney General James I. Barnes said he was reopening the investigation. Acknowleding that there were jurisdictional problems, Barnes said, "If we don't have jurisdiction, we will just share whatever information we find."

Barnes also raised the possibility that Preferred Equities land advertisements that appeared in a Dusseldorf financial newspaper may be misleading. If so, Barnes said, he will order the firm to cease such advertising. Failure to follow such an order could result in criminal charges against Preferred.

The land in question was once an agricultural oasis in the Nevada desert some 60 miles west of Las Vegas, on the road to Los Angeles. Only about 100 residences are actually up out of the 15,000 lots in the development, which is called CalVada. Promoters say it will be a year-round community with schools, golf courses and other recreational facilities.

Some of those facilities, like one golf course, are already under construction or completed. The development is surrounded by barren desert that stretches in both directions toward Las Vegas and Los Angeles.

In the promotional brochures sent to the Germans who bought the land, the development was described, seven years ago, as "the open door to the uncluttered wilderness parks, unbelievable natural beauty . . . on the fringe of the fasted growing metropolitan area in the United States."

The chief target of the German's ire is Leonard Rosen, who ran an investment fund called Parfund and, according to federal and state officials, ran Preferred Equities at the time of the sales to the Germans.

Rosen went to Germany and sold shares in Parfund, which he said was a firm that was investing in land in the United States.

But when the German government stopped the Parfund sales in Germany, Rosen talked many of his German customers into taking deeds to Nevada land instead of refunds on their Parfund shares.

The Germans said Rosen articially inflated the value of the land by selling it to himself though a complex trail of dummy corporations. Thus, they claim, they were not getting land valued at anything near their initial investment.

Then, many of the Germans began receiving large tax bills from Nevada for their holdings. A large number of the Germans, predominantly retired people who had invested a significant part of their life savings, could not or would not pay their taxes.

As a result, last October Nevada auctioned off the land belonging to about 100 German citizens after the holdings were seized for failure to pay taxes.

Preferred Equities bought back all of that land an average price of about $800 a lot. The lots had been valued at about $5,000 when first sold, or traded, to the Germans. A week after the repurchase, Preferred offered to sell the same land back to the Germans at the new, lower, price plus some added handling charges.

While federal officials were investigating Rosen in connection with the German transactions, an Internal Revenue Service audit revealed that he had bot paid taxes on two large land sales netting him in excess of $5.5 million.

Early last month, Rosen pleaded no contest to the tax evasion charge. A federal judge in Las Vegas revealed that Rosen had made a plea bargaining arrangement with federal authorities investigating him on the German situation and other alleged tax evasion schemes involving off-shore tax havens and companies.

Rosen is scheduled to be sentenced Monday and is expected to begin cooperating with federal authorities soon after.

The recent advertisements appearing in Dusseldorf had Preferred Equities looking for agents to sell their Nevada property in Germany. The ad says that the agents could earn profits into "six digit figures," and describes inspection flights for prospective agents to Las Vegas.

State Department officials here say German citizens have been popular targets for land sales schemes in the U.S. because Germany is a "hard currency" country - meaning that its currency is in demand around the world.

"Germany is open to this kind of abuse," said one State Department European expert. "It's a favorite target for hucksters of all kinds."

But, he added, the German government has not formally appealed on this matter to the State Department, although acknowledging that the German consulate in San Francisco was taking some action through state agencies in Nevada.