Anyone -- An Iranian citizen, a foreign tourist or a Soviet intelligence officer--can stroll up to the corner newspaper shacks in the bazaars of downtown Tehran and for a few rials buy a 13-volume paperback archive of secret U.S. documents on American relations with Iran from 1966 to 1979, all purportedly taken from the U.S. Embassy when it was seized in November, 1979.

Two months ago the first American journalists in Iran since the 52 hostages were freed in January, 1981--journalist-activist William Worthy and his free-lance television crew gathering documentary footage for CBS--bought a set. But last month, when they shipped one complete and one partial set of paperbacks back in their luggage, Customs and FBI officials in Boston seized the books, citing the federal statutes governing the theft of government property.

Last week Worthy and his colleagues, Randy Hope Goodman and Terry Taylor, represented by the American Civil Liberties Union, filed suit against the FBI and Customs, asking a federal court to order the return of the confiscated books and to declare that the seizure violated the First and Fourth Amendments.

The Justice Department has 60 days to respond to Worthy's suit. According to Justice sources the Reagan administration is trying to decide whether to use this as a trial case to establish that any possession or publication of classified material is illegal, although officials have yet to decide whether to prosecute the three journalists.

According to these sources the Justice Department may argue that, despite their public availability in Tehran and elsewhere, the paperbacks contain photocopies of more than a thousand pages of government documents and reports that are still properly classified.

Although several of the documents have been circulated in the United States, most have never been printed here. Justice Department sources say the department may oppose the civil suit and hopes to prevent the return of the documents to Worthy and his colleagues and to establish a legal rationale for such seizures where non-government officials possess copies of classified materials.

Another set of 12 volumes, shipped separately by the journalists, was made available to The Washington Post, which obtained the 13th and latest book from an Iranian source in this country.

Although not each of the more than 1,000 pages of documents could be authenticated, knowledgeable U.S. diplomatic, intelligence and military sources who insisted on anonymity confirmed that all the documents bound in the 12 volumes brought back by Worthy appear to be genuine and consistent with the classification procedures, special routing instructions and communications formats used by the State Department, CIA and Defense Department. Sources familiar with the documents at the time they were prepared also confirm the accuracy of the content of most of the documents.

Some officials, however, cautioned that Iranian student groups in the United States previously have circulated faked documents individually, including one letter purportedly signed by Zbigniew Brzezinski, President Carter's national security affairs adviser. None of the documents cited as possible fakes appears in the bound volumes.

In addition to the exposure the documents have received in Iran, U.S. intelligence officials say they believe that the Soviet Union has secured copies not only of the published documents but also of other materials in the embassy at the time of the takeover.

U.S. intelligence officials say they believe the most damaging aspect of the Tehran papers occurred when they became available in Iran, compromising methods and sources and other coded messages transmitted at the same time but not captured in the embassy takeover.