The Jewish Agency, a quasi-governmental body that has brought 630,000 Jewish immigrants to Israel from the former Soviet Union since 1989, announced tonight that Russian authorities have revoked its accreditation and notified local jurisdictions that the agency no longer is authorized to function in Russia.

There was no clear indication of Russia's intentions and no explanation from Moscow. But the potential stakes were seen in Israel as high.

Russian immigration has changed the face of Israel, adding nearly one-fifth to its Jewish population and infusing the state with one of the world's most productive flows of human capital. Before the thaw that accompanied the Soviet Union's final days, the Moscow government's sharp restrictions on emigration -- and ill-treatment of Jewish "refuseniks" who could not leave -- were a major source of friction with the West.

An estimated 1.4 million Jews remain in the former Soviet Union, 600,000 of them in Russia, and Israel had projected until now that they would continue to make new homes in Israel at last year's rate of 65,000 for several years to come. Officials here have observed no slowdown in Russia's distribution of exit visas, and they do not foresee a return to Russia's old bans on emigration itself, but they said most Russian Jews could not readily leave without the practical and financial assistance of the Jewish Agency.

Israeli officials said they were uncertain of the origins of the present impasse, and the Russian ambassador here qualified it as a bureaucratic slipup. But Israelis voiced two theories about what is happening.

One focused on the growing nationalist cast of a Russian election campaign that is threatening to unseat President Boris Yeltsin. The second looked to bilateral tensions and the bitterness of the new foreign minister, Yevgeny Primakov, at Israeli moves to keep Russia far from its desired role at the center of Middle East diplomacy.

A third explanation -- mere misunderstanding -- prevailed at first when the Jewish Agency lost its legal accreditation on April 4, which effectively terminated its right to operate offices, hold meetings and stage other activities in Russia. Agency officials treated it as a slipped formality and discouraged Israeli reporters from writing about the change.

Other signs -- including closure of the agency's Birobidjan and Makhachkale offices in the Russian hinterland, a Justice Ministry notice to local authorities about the loss of accreditation and an increase in vandalism directed at agency properties -- began to convince them otherwise as the month wore on.

Avraham Burg, the agency's chairman, decided to make public his protests after police and local government officials descended on a Jewish Agency gathering today in Pyatigorsk, an important regional emigration center in the northern Caucasus, and ordered the meeting to break up. Three Israeli representatives of the agency were asked to leave town.

"If this is just a bureaucratic stupidity, I will be happy," Burg said in an interview, "and if it is something else, we shall be ready in the international arena with the Jewish voice, Jewish pressure."

"We are working in the former Soviet Union under two assumptions," he added. "The first one is that the right of the ancient Jewish people to repatriation is a given, and the second one is that the constitutional, basic, elementary right of family reunification is {Russia's} passport to the free world. Without this you are not a Western modern country."

Burg said he had summoned the Russian ambassador to Israel, Alexander Bovin, for what became a sharp meeting last week. Burg said the ambassador assured him that the difficulty was merely technical.

Neither Bovin nor any other Russian diplomats here, nor officials in Moscow, could be reached for comment tonight.

Burg and Prime Minister Shimon Peres agreed to take the position that there can be no link between the agency's travails in Russia and any bilateral disputes between the Moscow and Jerusalem governments on the grounds that it affects the human rights of individual Jews and the broader interests of the world Jewish community. Foreign Ministry officials said tonight that they would play no role in protesting the change in Russian policy, and Burg planned to fly to New York Wednesday to confer with American Jewish leaders on possibly bringing pressure to bear in Moscow. Alla Levy , chief of the Jewish Agency's efforts in the former Soviet Union and a 1970 emigrant, said today's crackdown in Pyatigorsk was especially sensitive because that city is one of 10 from which Russian Jews fly directly to Israel.

Several irritants trouble Israeli-Russian relations, and Primakov rebuffed a meeting request last month from Foreign Minister Ehud Barak. A specialist in the Arab world, Primakov is seen as resenting the combined efforts of Israel and the United States to squeeze Moscow out of its place as co-sponsor of regional peace talks.

Israel acknowledges, in addition, that it has been slow to transfer legal rights to Russia from the former Soviet Union's valuable land holdings in Jerusalem. Additional frictions arose at Israel's treatment of Russian visitors at passport control points after police found evidence that Russian organized crime had made inroads here.