A former editor for the American Nazi Party is registered with the Justice Department as an agent for the Saudi Arabian government and says he received $20,000 from the Saudis last June for an anti-Zionist book published two years ago.

William N. Grimstad says in registration papers filed Nov. 15 that he received the money as a "gift or honorarium apparently in appreciation" for his book, "Antizion." The book is a collection of anti-Zionist and anti-Jewish statements attributed to famous public figures throughout history ranging from Winston Churchill and Mark Twain to Napoleon and Cicero.

Grimstad was managing editor in the early 1970s of White Power, the bimonthly publication of the American Nazi Party, now the National Socialist White People's Party.

His book is dedicated to the late King Faisal of Saudi Arabia, described in the frontispiece as a "distinguished statemans and humanitarian who in this New Dark Age never lost insight into the hidden causes of world upheaval."

Several representatives of the Saudi embassy here, however, say they have never heard of Grimstad. They said they were unaware that he is officially registered as an agent for the Saudi government and know nothing of the $20,000 he claims he received.

"The embassy says it has had no contact with Mr. Grimstad," said Mark Helgeson of the Saudi Arabian Information Office.

Grimstad, reached by telephone at his home Geneva, N.Y., said he received the $20,000 unsolicited, by check last June. He said he registered as an agent of the Saudis five months later without notifying them, and that he registered as a legal precaution "because of receiving the money."

"The money came to me under very mysterious circumstances," he said. "I'm mystified by the whole thing."

He said in a letter after the telephone call that he now believes the money may have been planted by a "covert unit of Israeli Intelligence in a misguided effort to discredit the Saudis . . ." He said he came to this belief after receiving press inquiries triggred by disclosure of his Justice Department registration statement by the Anti-Defamation League, an element of the Jewish service organization B'nai B'dith that monitors anti-Jewish and anti-Zionist activities and individuals.

ADL general counsel Arnold Forster scoffed at Grimstad's speculation.

Grimstad "is known to us as a professional anti-Semite who has been affiliated with the most outrageous un-American operation in the political underground of our country," Forster said yesterday. "The lie he offers about the ADL being the source of his money is equaled only by its implausibility."

Grimstad refused to discuss details of how he received the $20,000."I have fairly firm indications of where it came from," he said, "but I'm not in a position to discuss it now."

In his sworn and notarized registration statement, he said he received a check for $20,000 from Saudi Arabia "through [the] embassy in Washington" last June. He said an "explanatory note" accompanying the check was in the form of a receipt, "which was endorsed by me and returned to the embassy."

Grimstad described himself in the registration statement as a writer and historian. On behalf of the Saudi government, he said, he planned to do 'historical research into all aspects of the Zionist colonial incursion into Palestine, aimed at inclusion in a screenplay or teleplay, to be produced for exhibition primarily to students."

Grimstad is one of 16 individuals and organizations, including several well-known public relations and law firms, registered as agents for the Saudis. Individuals or organizations doing publicity, legal work or lobbying for foreign countries are required by law to register with the Justice Department.

Grimstad says he now plans to "deregister" because of his doubts about the origin of the $20,000. A Justice Department spokesman said yesterday the foreign agents registration unit has not yet received a formal deregistration request.

The spokesman also said Grimstad's registreatration statement was vague and lacked copies of a contract or letter from the Saudis requesting Grimstad's services.

Grimstad's book, "Antizion," was published in 1976 by Noontide Press, a California publishing house run by Willis A. Carto, a well-known anti-Zionist and treasurer of the ultra conservative Liberty Lobby here. The book quotes several hundred famous historical figures, many of whom said international Jewry is embarked on a conspiracy to dominate the world.