An author at the Institute for Policy Studies has touched off a diplomatic flap among several NATO allies by disclosing a classified document that describes U.S. contingency plans to deploy nuclear weapons in Canada, Iceland, Bermuda and Puerto Rico.

Nuclear weapons expert William M. Arkin has generated considerable publicity abroad by providing the classified document to foreign officials, causing some embarrassment here because U.S. officials had not discussed the plans with the governments involved. The New York Times said in an article yesterday that Arkin had provided it with a copy of the 1975 document on U.S. nuclear contingency plans.

Administration reaction was muted, and officials would not say whether there would be an investigation of the leak. Pentagon spokesman Jim Turner said only that Arkin, as a private citizen, "doesn't fall under our purview to investigate."

"The U.S. does not comment on contingency plans . . . or on the authenticity of alleged classified documents," State Department spokesman Bernard Kalb said yesterday. The weapons involved are nuclear depth charges called B57 bombs, which weigh about 500 pounds each, according to the IPS, a liberal research organization. They would be dropped by aircraft to destroy submarines or block their underwater passage, the group said, adding that the U.S. contingency plan also includes Spain and the Philippines.

Arkin, a former Army intelligence analyst in Berlin, has published several books on nuclear issues and is known to journalists and government experts as an outspoken critic of some U.S. nuclear strategies. He has made extensive use of classified and declassified documents and recently sparked a controversy in West Germany by disclosing the deployment of U.S. nuclear land mines there.

Thomas B. Cochran, a scientist with the Natural Resources Defense Council and occasional coauthor with Arkin, compared Arkin's action with Daniel Ellsberg's 1971 disclosure of the Pentagon Papers, a classified study of U.S. policies in Vietnam. Cochran said the government "overclassifies" many such documents and that he expects the administration to investigate the leak.

While some people will object to the release of classified material, he said, "others will conclude he Arkin handled the issue responsibly by telling the countries involved what is going on."

"The government's kind of got egg on its face. They go around and explain that this paper doesn't mean anything. But if it doesn't mean anything, what harm has Arkin done by releasing it?"

Arkin created a stir in Iceland when he gave the document to officials and reporters there in December. Iceland has a strict policy that no nuclear weapons can be brought into the country in peacetime and only with the government's permission in the event of war.

When the story broke there, Prime Minister Steingrimur Hermannsson demanded an explanation from U.S. authorities, and his foreign minister said that such plans represented "a clear breach of the defense treaty" between the two countries.

"It came as a total surprise," said a counselor at the Icelandic Embassy. "There was quite a lot of press coverage and debate."

But he said his government is "satisfied" with U.S. assurances "that no such deployment would be made in Iceland without Iceland's approval." He said Iceland was told that the need for such approval was included in a part of the 1975 document not distributed by Arkin.

Similar news reports in Canada followed Arkin's visit there last month. While Canadian officials minimized the matter, Adm. Robert Falls, a former Canadian defense official, told Maclean's magazine that the reported U.S. policy was "immoral" for failing to consult with the government in Ottawa.

Canadian Embassy spokesman John Fieldhouse said yesterday "there are no plans for the stationing of nuclear weapons on Canadian soil. If any contingency plan were to come forward in the future . . . no such plan could be implemented without prior consultation with the Canadian government."

He said External Affairs Minister Joe Clark told the House of Commons yesterday that Canada "would reserve the right to refuse the stationing of such weapons."

U.S. authorities are barred by treaty from deploying nuclear weapons in Puerto Rico. But the Puerto Rican Bar Association disclosed last year that storage facilities and a team of trained military personnel were in place there to receive the nuclear depth charges.

A State Department official said that Arkin had caused "a one- or two-day sensation" in each of the countries he visited, but that the adverse reaction quickly died down.