Egyptian President Anwar Sadat received assurances from West German Chancellor Helmut Schmidt in private talks here last night that Bonn was ready, at least in principle, to provide additional economic aid to Cairo. But the West German government made it clear, officials stress, that they want such aid to be part of an international effrot including not only the United States and Japan, but other European countries as well.

Bonn's emphasis on linking increased aid to Cairo to a collective effort, especially involving other European states, is designed to help West Germany support the thrust of the new Egyptian-israeli peace treaty and U.S. efforts to develop financial helpers outside of Washington, and at the same time no jeaopardize Bonn's relations with the rest of the Arab world.

As the wealthiest country in Western Europe, West Germany is being looked to by both Washington and Cairo to chip in with a sizable dose of aid. Schmidt spokesman Klaus Boelling today said the United Staes has thus far made no frmal or even indirect specific financial requests of Bonn, a fact the U.S. officials here confirm.

The situation, however, eventually could provide a tough test of Schmidt's foreign policy. It is not at all clear that other West European states will contribute to the multibillion dollar "Marshall Pan" for Egypt envisioned by Sadat and the Carter administration. Without the cooperation of other Europeans, Boon would have no protective shelter against potential Arab retaliation.

France has already indicated a reluctance to offend Cairo's enemies in the Arab world and so action by the nine-member European Common Market as a unit on the aid question is not likely. Today, Boeling clearly left open Bonn's ability to maneuver around this by aknowledging that any new collective aid "does not neccessarily have to take place in the framework of the European Economics Commnunity."

Boelling said that money "figures were not mentioned" during the more than three hours the two leaders spent toghether. He also said specialists-though he did not say from which countries-would get together soon to consider how an aid plan might be put together. He said this probably would not be finished before the next Western economic summit meeting in Tokyo June 28.

Privately, Foreign Ministry officials say they don't know how the conditions imposed by West Germany-namely the participation of other european countries-would be overcome by Bonn if there is no agreement by those other countries to participate. They added, however, that it was useless to speculate on that now because the situation was still quite fresh.

If only a few countries apart from the United States agree to participate, Schmidt would face a tough decision: either displease Washington, which is so far bearing the exclusive financial burden of the treaty, or risk the wrath of Arab oil states.

Although Sadat has visited West Germany four times in the past four years and seems very comfortable here, sources close to the chancellery say this trip was Sadat's idea.

Egypt, for a number of years, has been the recipient of the second largest dose of economic aid handed out by Bonn. India ranks first. Since 1977, Cairo has been getting about $135 million from Bonn annually in economic aid.

Sadat has talked about a $15 billion aid plan over a three-year period. But here, specialists are dealing with smaller numbers. Out of roughly $5 billion treaty cost, $3 billion is expected to be U.S. aid to Israeli and about $1.5 billion, U.S. military aid to Cairo. The remaining $500 million is what Bonn planners believe should be financed by the international effort.