Syrian President Hafez Assad is not just boycotting the Cairo peace talks but he is refusing to have any dealings with Egypt as long as President Anwar Sadat holds power in Cairo, well-informed Syrian sources disclosed today.

Despite this unyielding position that emerged following Secretary of State Cyrus Vance's two hour meeting with Assad yesterday, the Syrian sources say that Assad remains willing to seek a negotiated Midle East settlement once Sadat is out of office.

Moreover, Assad apparently is determined to keep his communications open to the United States - despite voices in the press and the Syrian power structure blaming Washington for engineering Sadat's peace initiative.

Authoritative Syrian sources reject the argument that Assad's boycott policy amounts to burning bridges and isolating Syria. Nor do they accept suggestions that Syrian policy may eventually force Sadat into a separate peace with Israel - the very course Syria has denounced since his visit to Jerusalem.

From the Syrian viewpoint, such an outcome is doomed "because you cannot make peace without the Lebanese, Jordanians, Syrians and Palestinians," as one senior Syrian official put it.

Thus, uncharacteristically for a leader renowned for prudence, Assad apparently has rejected out of hand any possibility that Israel could produce concessions to Syria and the Palestinians in return for an overall settlement.

The Syrians deny that their approach is emotional. It is evident, however, that the government here is still smarting from the unhealed wound inflicted by what Damascus considers Sadat's "betrayal" in going it alone without prior consultations with the other Arabs.

Symptomatic of the Syrian mood was the government communique issued after Vance's visit here yesterday which said Sadat's Jerusalem visit had created "a sick state of affairs which should be removed in order for the area to recover its good health."

A Western observer remarks that "for Assad it's inconceivable that Sadat should succeed. Even if he did, it will be considered a failure; it would be a sick success done without the Arab consensus and by breaking Arab ranks."

"Prostrating oneself before the enemy is not the road to peace, but to capitulation," the Syrian communique said, quoting Assad as having told Vance that a real peace "cannot be begged for."

Despite seeing contradictions, the Syrians insist that Damascus is not guilty of intransigence and that at the recent Tripoli conference of anti-Sadat leaders Assad had deliberately refused any radical language leading to a return to the Arab ideological rifts of the 1950s and 1960s.

In private conversations the Syrians sought to discount the surge of world opinion in favor of the Cairo talks and warned of "manipulation of the Zionist lobby." One official said, "this is an Arab issue and what matters is what most Arabs feel."

In other developments, news agencies reported the following:

King Hassan of Morocco began diplomatic moves for an emergency Arab summit conference to consider the outcome of the Cairo talks, according to government sources in Rabat.

Two of the king's closest advisers left Morocco with messages from Hassan to other Arab leaders, including PLO leader Yasser Arafat, the sources said. A government spokesman said the messages were intended to restore Arab unity.

In the Persian Gulf emirate of Sharjah, a bomb reportedly damaged an Egyptian office in apparent protest against the start of the Cairo meetings.

Saudi and Syrian troops of the Arab peacekeeping force in Lebanon clamped tight security around Egyptian institutions in the country.

A strike called by Palestinian groups, and supported by Lebanese leftists, closed schools and shops in some areas of the predominantly Moslem area of West Beirut.