Israel, besides failing to achieve its sought-after "breakthrough" toward an agreement on Palestinian autonomy, was unable in the latest talks even to get a fix on Egypt's intentions regarding the issue between now and when Israel is to complete its withdrawal from the Sinai Peninsula on April 25, Israeli sources said today.

An Israeli participant in the ministerial-level Cairo talks, which broke up yesterday without substantive agreement, said a main purpose was to test the Egyptians and to come back with a reading of their tactical plan for the next five months.

Failure even to reach agreement on two or three sections of a general declaration of principles frustrated that endeavor, however, and apparently left Israel in the dark about Egyptian intentions.

"We heard all the assurances, comforting as they are, from Egypt that peace is unshakable and that Camp David is the only path," the Israeli official said. "Now, in a period of transition in Egypt, we welcome those statements. But we wanted to see how the Egyptian attitudes are translated practically in the autonomy negotiations."

Some Israeli officials privately have expressed the fear that Egypt's strategy is to keep the autonomy talks inconclusive until April 25 so that it cannot be accused by the rest of the Arab world of concluding a separate peace with Israel solely to win back the Sinai.

According to that theory, Egypt also would be reluctant to agree to autonomy principles very long before April 25, because they presumably would be rejected by the Arab states and Egypt no longer would be able to offer hope for a comprehensive Middle East peace.

Israel has said it is prepared to continue autonomy negotiations after April 25, but there have been no solid assurances that Egypt has the same intentions. By some accounts, it might let the matter slide.

While members of the Israeli delegation attempted to put as good a face as possible on the two-day session, emphasizing that it was not realistic to expect dramatic progress in such a short time, their disappointment in the outcome was unmistakable.

Israel's chief negotiator, Interior Minister Yosef Burg, said it would be "exaggerated" to characterize him as "much more optimistic," and indicated that he anticipates long and difficult negotiations ahead.

Members of the Israeli delegation said they had advanced "thoughtful and attractive" proposals to the Egyptians which had not been accepted, although they will be discusssed by lower level "working committees" that will resume negotiations on Sunday. The Israeli officials refused to disclose any details of the new proposals, although they were understood to deal with the size of the proposed Palestinian autonomy council and the scope of its authority.

The fact that the negotiations have been kicked back to the working committees appeared to be a regression in Israel's negotiating strategy. Prime Minister Menachem Begin last month advocated a new round of ministerial-level meetings largely on the argument that the committees had become bogged down in technical details.

Israeli officials today stressed that the Cabinet ministers cannot devote their time to marathon negotiations, and therefore the working groups had to be reconvened.

From the beginning of the Camp David accords, the powers and responsibilities of the autonomous council have been a major sticking point, along with such issues as internal and external security, land and water rights and voting rights for the 100,000 Palestinians who live in East Jerusalem, which Israel annexed in 1967.