Harvard Square bookstores which have continued to sell Fanny Hill will be "virtually defenseless" in criminal prosecution if the book is ultimately found "obscence, impure, and indecent," a spokesman for the state Attorney General's office said last night.

While Suffolk County Superior Court's action of Feb. 10 was merely an order of notice that there is probable cause for banning John Cleland's 18th century novel, an assistant to Attorney General Edward W. Brooke said that this was "effectively a restraining order on sale of the book," and that those who have continued to sell it have placed themselves in a "perilous situation."

If the final decision, after appeal to the Supreme Judicial Court, declares that the book will be banned in Massachusetts, anyone who has sold Fanny Hill since Feb.10 will lose the usual defense that he had no knowledge of the book's obscenity.

The next stage in the battle over Memoire of a Woman of Pleasure comes March 11, when the order is returnable before Judge Eugene A. Hudson and anyone who objects to banning the book including the publisher, must present himself.

G. P. Putnam's Sons, which published Fanny Hill in June, 1963, was reported yesterday to have retained counsel in Boston to defend the book. Putnam's has said that it will seek experts to defend Fanny Hill's "literary and historic merit."

Libraries Join Dispute

The Intellectual Freedoms Committee of the Massachusetts Library Association said yesterday that it would probably join the Civil Liberties Union in filing an amicus curiae brief at the appellate level. The Association is concerned because "distribution" of a book has been interpreted in censorship cases to include libraries.

Prosecution of Fanny Hill was recommended to Brooke by the Massachusetts Obscene Literature Control Commission, which has the authority to report violations of he Commonwealth's obscenity laws. The commission is made up of three clergymen, a high school principal, a police chief, and a newspaper publisher. Joseph Zabriskie, chairman of the Commission, explained yesterday that action had been taken against Fanny Hill when a woman whose 15-year-old son had bought a copy brought it to their attention.

The Commission did not call in outside testimony to make its decision, since "It is the opinion of the rank-and-file in the state" that matters, and, Zabriskie said, they have on many occasions endorsed the Commission in its work to seek out pornographic literature "on the stands for children to read.