A powerful car bomb rocked the port city of Sidon in southern Lebanon tonight, killing one person and wounding 30, including a leading Sunni Moslem figure who was reported in critical condition after surgery at the American University Hospital here.

The explosion came as Israeli troops continued to move military equipment southward in the Sidon area in the first step of what is eventually to be a complete withdrawal from Lebanon.

Mustafa Saad, his wife and a daughter were wounded when the booby-trapped car was detonated outside the five-story building in which they lived. Saad, leader of the anti-Israeli Nasserite Organization, is the son of the late Maarouf Saad, who was shot dead during a fishermen's demonstration in Sidon in 1975, an incident that helped spark the Lebanese civil war.

Prime Minister Rashid Karami immediately blamed Israel for the explosion, telling reporters that "I have said the enemy will try to foment such trouble." He and other Lebanese leaders have warned that Israel's decision to withdraw from Lebanon without a joint agreement on security provisions would lead to sectarian violence.

Karami and other Lebanese officials also have accused Israel publicly of trying to foment friction and sow discord among the people in southern Lebanon -- a charge Israel denies.

State-run Beirut radio said Saad was flown by a U.N. helicopter to Beirut, at the request of President Amin Gemayel, for brain surgery. The radio and reporters in the area said an Israeli helicopter prevented the takeoff of the U.N. helicopter until nearly four hours after the explosion, as the Israelis tried to talk the rescue team into flying the prominent foe of the Israeli occupation to a hospital in Haifa, Israel.

Anti-Israeli sentiment was running high in Sidon tonight, reporters there said, with crowds of demonstrators shouting slogans against the occupation.

Israel's Cabinet decided last week on a three-stage withdrawal of its troops, who have occupied the southern third of Lebanon since the 1982 invasion. The first stage, to be completed by Feb. 18, will move the Israeli line, now at the Awwali River north of Sidon, about seven miles south, returning Sidon to Lebanese control.

Saad was chairing a meeting of Sunni and Shiite Moslems when the blast went off. The meeting reportedly was part of a series of efforts by Moslem and Christian leaders to avert sectarian violence before the Lebanese Army can fill the vacuum created by the Israeli pullback.

Sidon residents watched today as one convoy of Israeli military vehicles moved southward and another rumbled east toward the Christian town of Jezzine. Reporters in the area said the Israeli troops started setting up positions along the edge of the area they vacated.

Associated Press photographer Max Nash, allowed by the Israeli Army to observe withdrawal preparations along the Awwali, 20 miles south of Beirut, said one of the biggest Israeli bases on the river had been almost dismantled by mid-afternoon. Lebanese reporters said trucks were moving out in convoys of three or four from Mar Elias, the largest Israeli camp north of Sidon, under the escort of an armored personnel carrier and a modified Centurion tank.

Security talks between Lebanon and Israel are to resume in the Lebanese border town of Naqura on Tuesday under U.N. auspices. The talks broke down Jan. 7 following disagreement on the effectiveness and future role of the Lebanese Army and the deployment of U.N. peace-keeping troops. Differences also persisted on the role of the Israeli-backed South Lebanon Army, which Israel wants to be assigned security functions in a border strip adjacent to the Israeli border.

U.N. Undersecretary General Brian Urquhart has been shuttling between Israel and Lebanon in an effort to gain agreement on the zone of operations of an expanded U.N. force.

Israel says it distrusts the Lebanese Army's ability to control southern Lebanon and guard northern Israel against terrorist attacks.

Lebanon's Cabinet heard reports today by the Army commander in chief, Gen. Michel Aoun, on plans to move the Army south, and Karami said it was prepared to carry out its mission and move into place once it was ordered to do so.

The Army, however, has been virtually paralyzed in the face of Moslem militia disorders in west Beirut.

Although Israel has not come up with a complete timetable for withdrawal, as Lebanon requested, Urquhart told Lebanese leaders today that the incomplete schedule, coupled with Lebanese proposals for U.N. and Army deployment south of the Awwali River, the line Israel is abandoning, could provide a good basis for negotiations at Naqura Tuesday.

The independent Beirut daily newspaper An Nahar said today that Urquhart has brought to the Beirut government Israeli assurances -- but not guarantees -- that its allies in southern Lebanon would not try to exploit the fragile mosaic of religious groups there to set off sectarian hostilities.