Leaders of radical Arab countries opposing Egyptian President Anwar Sadat's Middle East peace diplomacy are scheduled to hold a summit conference in Libya today in an effort to subvert his initiative.

Barring last minute changes, the Tripoli summit will be attended by the heads of state of Algeria, South Yemen, Syria and Libya. Iraq announced last night that it would be represented at the summit by Housing Minister Taha Yassin Ramadan, who is a member of the ruling council. Also in attendence would be the leaders of the Palestine Liberation Organization.

Iraq, apart from Libya the most radical of all Arab governmets, has called for a backup summit meeting to Baghdad nextt week, presumably to continue pressures on Sadat and draw up battle in the Arab world.

Arab broadcasts monitored here suggested yesterday that Saudi Arabia may send representatives to the Libyan summit to exercise moderation at what is shaping up as a meeting designed largely to under cut Sadat's peace initiative.

The broadcasts quoted Abu Mayzer, spokesman for the PLO executive committee, as upon returning to Damascus from Saudi Arabia that the Saudis would go to Libya today. U.S. specialists discounted these reports.

Most conservative and moderate Arab governments have taken the position that they would not take part in any Arab summit unless it is attended by all 21 members of the Arab League.

The United Arab Emirates, a wealthy and conservative country, went so far as to cancel celebrations of its national day Friday. A spokesman for the Emirates embassy here said the action was connected to the Middle East situation.

In the midst of the Arab world's political disarray, Jordan's King Hussein called again yesterday for moderation and "restraint".

Senior Jordanian sources privately expressed serious concern that the escalating anti-Sadat momentum in the Arab world may drive the Egyptian leader into an isolated where he might concluded a separate peace agreement with Israel.

American officials specializing in Middle East affairs noted that only the most radical of Arab states would be attended the Libyan summit. The proposed Baghdad conference, they suggested, may never take place.

While the summit represents a measure of success for the opponents of Sadat, their action also appears to have broken down the trend toward unity in hte Arab world. Even so, American officials here said they expected Syria and the PLO to play a "relatively moderate" role at Tripoli.

Most of the moderate Arab countries are now seen as awaiting signs of Israel's flexibility to match the boldness of Sadat's trip to Jerusalem and his formal acceptance of Israel.

Sadat's intiative was a "dramatic gesture which changed the entire Middle East equation," one U.S. analyst said, "But then again nothing tangible has come out of it, so Arabs are waiting."

The Libyan summit was not expected to isolate Sadat in the Arad world, but its outcome may lead to a polarization in the Arab world. At the same time. Sadat's Cairo conference on Dec. 13 - and it will involve as of now only Egypt, Israel, the united States and the United Nations - was not expected to advance Sadat's intiative without significant Israeli concessions that would allow moderate Arabs to join in a later stage.