Fresh and virulent attacks on Jewish mathematicians in the Soviet Union pose a serious threat to the exchange agreements in science and technology between the United States and the Soviet Union.

"Mathematicians who are Jewish are being treated worse than other Jews in Russia," said one Carter administration source who asked not to be identified. "The situation with regard to Jewish mathematicians is potentially explosive."

In the last year, Jewish mathematicians have been forbidden to publish articles and travel abroad to attend international meetings. Jewish students have been barred from universities, even when they show great talent for mathematics, sources said.

Jewish students already studying in universities have suffered automatic failures in examinations. Those asking to go on for postgraduate study have found their way into the mathematics institutes blocked, they said.

"We even hear reports from travelers and recent emigres that histories of Soviet mathematics are being rewritten to exclude the accomplishments of Jews," said Dr. Kenneth Hoffman, chairman of the mathematics department at Massachusetts Institute of Technology. "That's like leaving Einstein out of a history of physics accomplishments from 1900 to 1950."

Americans in contact with Soviet mathematicians say the treatment of Jews in the field of mathematics is worse than their treatment in any other science.

The suppression of Jews in mathematics appears to come from two leaders of the Soviet mathematics community and not from the political leadership. American scientists recently in the Soviet Union say the attacks on Jewish mathematicians are not an outgrowth of any government policy.

One of the two mathematicians allegedly suppressing Jews is identified as Lev Semenovich Pontryagin, who represents the Soviet Union in the International Mathematical Union, directs the editorial board that decides whose articles get published and edits the journal Matematicheski Sbornik. Pontryagin also controls the votes on the National Committee of Soviet Mathematicians, which determines the travel of Russians in the field.

"Pontryagin and a few rabid colleagues of his apparently feel that Jews don't represent Soviet mathematics," said a source close to U.S.-Soviet exchange agreements. "These people somehow impute a possible disloyalty of Jews who want to emigrate" and see a conflict between this desire and the development of a "true native Soviet mathematics."

Detailed accounts of mistreatment of Jewish mathematicians are found in two reports taken out of the Soviet Union by recent emigres to Israel and the United States. A paper written on the subjtct by mathematician Grigori Freiman, professor of mathematics at the University of Kalinin, was published in an underground journal in Moscow.

The first report discussed the general mistreatment of Jewish mathematicians. The second related the experiences of individuals.

The American Mathematical Society has protested the mistreatment of Jewish mathematicians in the Soviet Union and while the Carter administration has not made a formal protest, it is understood that complaints have been filed informally with the Kremlin.

It was reported last month that, in an escalation of organized protest by U.S. scientists of Soviet harassment of dissident academics, more than 2,400 American scientists have signed personal pledges to end or restrict their cooperation with their Soviet counterparts until Moscow releases two famous political dissidents from prison.

Science Magazine recently related that when mathematicians gathered in Helsinki last summer at the International Congress of Mathematicians to award Fields medals, the equivalent of Nobel prizes in mathematics, to their finest young researchers, four medals were given, but only three winners accepted. The fourth winner, a Soviet Jew named Gregory Margoulis, was not permitted to attend the meeting, the magazine said.

"In homage to his achievements, the entire audience rose to its feet," Yale University's George Mostow wrote, in a spontaneous gesture of admiration for the medalist who was so conspicuously absent."