Calling President Reagan's Middle East peace proposals "basically vicious," Soviet President Leonid Brezhnev today advanced his own peace formula, restated in a way that resembles the plan adopted at the recent Arab summit in Morocco.

The Soviet leader's six-point plan calls for Israeli withdrawal to pre-1967 borders, creation of a Palestinian state, and mutual pledges by the area's states to renounce the use of force and respect each other's sovereignty. He suggested that the settlement be guaranteed by the U.N. Security Council or its permanent members.

In a Kremlin dinner speech honoring visiting South Yemeni President Ali Nasser Mohammed, Brezhnev also implicitly raised the question of "the legal basis of Israel's existence" and coupled it with renewed warnings against an Israeli attack on Syria.

Diplomatic observers here said the speech, distributed by the news agency Tass, marked a major Kremlin shift following the Israeli invasion of Lebanon -- apparently seeking a diplomatic role to reestablish its influence and presence in the area.

After welcoming the peace proposal made at the Fez Arab summit, Brezhnev attacked the Reagan administration for allegedly having "actually sacrificed Lebanon to Israel." He said Reagan was now "in a hurry to consign the bloody tragedy to oblivion" by "pretending" to seek a settlement.

The American proposals, Brezhnev continued, "are basically vicious" because they envisage an administrative autonomy for the Palestinians and do not explicitly recognize the Palestine Liberation Organization as the sole legitimate representative of the Palestinian Arabs.

"In opposing the creation by the Palestinians of their own state, the Washington administration is thus also calling in question the legal basis of Israel's existence, as the decision adopted by the United Nations in 1947 provided for the creation on the former mandated territory of Palestine of two sovereign states--an Arab state and a Jewish one. Nobody has canceled that decision and none has the right to do so.

"It would be rash to think that this decision can be implemented only in its part concerning the creation of a Jewish state and indefinitely disregarding the part concerning the creation of an Arab Palestinian state."

Tonight's speech constituted the most authoritative Soviet pronouncement on the Middle East in several years as it outlined in detail the Soviet position. None of the elements was new but the plan has been packaged in a way apparently designed to win Arab approval at a time when issues are coming to a head in the region.

Nodding toward Saudi Arabia, Brezhnev mentioned free access to Jerusalem's holy places. He demanded Israeli withdrawal from the Golan Heights, a major Syrian concern.

Speaking about the recent Arab summit, he said, "We positively assess the principles for the settlement of the Palestinian issues, and of the Middle East settlement as a whole, which were adopted by the meeting."

The six-point plan includes:

* "The principle of inadmissability of seizure of foreign lands through aggression should be strictly observed. And this means that all territories occupied by Israel since 1967 . . . must be returned to the Arabs . . . .

* "The inalienable right of the Arab people of Palestine to self-determination, to the creation of their own independent state on the Palestinian lands which will be freed from the Israeli occupation . . . must be ensured in practice . . . .

* "The eastern part of Jerusalem . . . where one of the main Moslem holy shrines is situated must be returned to the Arabs and become an inseparable part of the Palestine state. Free access of believers to the holy shrines of the three religions must be ensured in the whole of Jerusalem.

* "The right of all states of the area must be ensured to safe and independent existence . . .

* "An end must be put to the state of war and peace must be established between the Arab states and Israel. This means that all sides in the conflict, including Israel and the Palestinian state, must commit themselves to mutually respect each other's sovereignty and territorial integrity . . .

* "International guarantees of settlement must be drawn up and adopted, the role of guarantors could be assumed, let us say, by the permanent members of the U.N. Security Council or by the Security Council as a whole."