President Carter's role in promoting an Egyptian-Israeli peace treaty has drawn unusual criticism from traditional friends in the Arab world and stony silence from others as well as the inevitable invective from known adversaries.

The angry reaction -- including the first known anti-U.S. attack on Jordanian radio and Syrian calls for economic sanctions against the United States -- comes against a backdrop of rumors of discord within the royal leadership of Saudi Arabia.

Taken together, the developments have inspired increased self-assurance within the Palestine Liberation Organization, whose leadership is reported relieved that the major Arab states seem determined to oppose Egypt.

The Palestinians' private nightmare once involved a move by Saudi Arabia, the conservative oil kingdom that is the United States' closest Arab ally, to desert the Palestinians and split Arab ranks to form a conservative alliance with Egypt, Iran, the United States and, implicitly, Israel.

But the Saudi attitude already had changed at last November's Baghdad summit conference, where Crown Prince Fahd went along with tough sanctions to be applied automatically should Egypt sign a separate peace. Then the attitude of Iran was reversed with the downfall of the shah and the emergence of a pro-Palestinian Moslem leadership.

Now Palestinian officials note that no one in the Saudi leadership is defending President Anwar Sadat and they assume, right or wrong, that Saudi Arabia will stop bankrolling Egypt once Sadat signs a treaty with Israel.

Recurrent rumors of a policy wrangle between pro-American Prince Sultan, the defense minister, and Prince Abdullah, the National Guard commander who questions overreliance on the United States, contribute to the growing impression that Riyadh is unwilling now to stick its neck out by going along with Carter, Palestinians say.

Palestinian analysts have been known in the past to make their interpretations fit their goals, and Arab attitudes frequently turn about with surprising swiftness. But for now, at least, the Palestinian leadership here seems convinced that Sadat and the treaty will not last and that Arab governments have accepted this reading pretty much as given.

Central to this theme is the treaty's plan for turning the West Bank and Gaza Strip into what the Palestinians denounced as a glorified Bantustan, a reference to black puppet states set up by South Africa.

The proposed treaty's plan for local autonomy is viewed as a cruel charade by Palestinians. Not only is the PLO rejected as representative of the Palestinians, but by definition such a self-governing territory would be deprived of any foreign or defense policy functions, and indeed Israeli troops would be regrouped and stationed on it sterritory, they complain.

King Hussein of Jordan, Long a U.S. ally, has again made it clear that he has no intention of geting involved in the proposed deal, according to authorized Jordanian sources.

A Western diplomat long acquainted with Jordan said, "The United States has got to come up with a lot more before the king is going to go along -- and the wherewithal is not going to be money. The American aid contribution to Jordan is peanuts compared to that of the Arabs."

Indicative of the king's hostility to the Carter initiative was a stinging attack on the United States -- the first in observers' memory -- carried on the government-controlled radio and television network only hours after the president announced the success of his mission Tuesday.

In Syria, an anti-U.S. mood was reflected in an editoial today in Al Baath, the newspaper of the ruling party of the same name, which said sanctions against Egypt were not enough. Sanctions against the United States also are needed, it said.

President Hafez Assad of Syria is one of the Middle Easths most prudent politicians, however, and Syria still finds the American connection useful in balancing the Osviet Union. The United States has played a crucial role in relaying messages between Syria and Israel and preventing clashes between the Jewish state and Damascus in Lebanon.