The Reagan administration remains determined not to ask Israel to turn loose the 735 Lebanese prisoners who are apparently the key to the release of Americans held in Beirut, but the United States expects Israel to free those prisoners without being asked, a well-informed White House official said yesterday.

"We figure that Israeli Prime Minister Shimon Peres can read our minds," the official said. "Peres knows what is happening here. He can understand the delicacy of the situation."

The White House official said that "certainly there are enough people over here of the Jewish faith who can read . . . who must be telling people over there in Israel , 'For God's sake, look what you're doing to public opinion' " in the United States.

The diplomatic minuet between the United States and Israel over the terms and timing of the release of the Lebanese prisoners has become a central issue -- and could become the central issue -- in a possible diplomatic denouement to the hostage-taking. Ironically, these two countries, which have built a reputation as the very best of international friends, both claim publicly to be barely talking to one another about an incident that has become a major foreign policy test for the Reagan administration.

Freeing the Lebanese prisoners, mostly Shiites, being held in an Israeli prison, has been the key demand of the hijackers holding the 39 U.S. passengers and crew and of Lebanese Shiite leader Nabih Berri, who has taken responsibility for the Americans.

Israel has insisted since the outset of the hijacking that it is willing to free the prisoners but, under present circumstances, only in response to a formal U.S. request to do so. The United States has persistently refused to make such a request. But at several junctures during the two-week crisis, American officials have made pointed remarks signaling their belief that Israel should release its prisoners. Early last week, administration spokesmen noted that Israel had said it would release them, and noted a U.S. statement of April 3 that holding the prisoners in Israel was a violation of international law. An Israeli television report last night that Israel will release its prisoners only after the Americans are freed made no mention of a request from the United States. There were hints from U.S. officials that Israel has signaled a willingness to execute such a sequential release without being formally asked.

The Reagan administration's reluctance to ask Israel to release its prisoners is based on the perception that this would be conceding to terrorists' demands. But the remarks yesterday by the White House official indicated that the United States would welcome an independent Israeli decision to let the prisoners go.

Noting that under Israeli law Peres cannot keep the prisoners for long, the White House official said: "If Peres is going to release these people anyway, why not, up front, do it? Wouldn't that play to the minds of the American people through the American press that Israel is helping the American people in return for the help the United States is giving to Israel?"

When asked if the United States is whispering this to its Israeli ally or suggesting it in some way, the official replied, "No! No!" But he added that Peres must be getting the message, particularly from American Jews.

Leaders of several American Jewish organizations did warn Peres last week that Israel's initial demand for a formal U.S. request was creating an impression here of insensitivity to the plight of the hostages. This warning is believed to have been a factor in Peres' telephone calls to Secretary of State George P. Shultz last Friday and Sunday, Israel's release of 31 Lebanese prisoners Monday, and Peres' letter Monday to President Reagan pledging solidarity with U.S. policy. Another factor may have been a Washington Post-ABC News Poll suggesting that the American public's support for close relations with Israel might be weakening.

Peres is believed to have softened the Israeli position in the letter to Reagan, saying that Israel will cooperate in any way the United States wishes.

Just as the Reagan administration has a problem in seeming to comply with the hijackers' demands, officials conceded, so Peres has a problem in keeping with the Jewish state's longstanding refusal to negotiate with terrorists or make concessions for hostages.

The U.S. administration does not want to press Peres because "he's got a helluva political problem and we know it," said the White House official, referring to tense relations within Israel's coalition government, and to public backlash against a recent swap of more than 1,150 mostly Arab prisoners in Israel for three Israeli soldiers.