Israel launched its most intense attack to date on besieged West Beirut and the city's southern suburbs today, as warplanes, gunboats, tanks and artillery pounded the area for 14 hours.

The massive bombardment finally was halted early this evening by the ninth cease-fire of the two-month conflict. The assault reportedly left 150 to 200 persons dead and more than 400 injured, according to the independent Beirut newspaper An Nahar.

There appeared to be many civilian casualties among today's victims. Scores of apartment buildings, office buildings and small houses and shops were severely damaged or gutted by the bombing. Fires continued to burn out of control for hours afterward.

The Palestinian news agency Wafa claimed that guerrillas had killed or wounded 80 Israeli soldiers, knocked out 30 tanks and troop carriers and shot down a plane and a helicopter in the day's fighting. Israel said nine of its troops had been wounded and denied that any aircraft had been lost.

In Damascus, a Syrian military spokesman said two Syrian soldiers were killed and four wounded in the fighting, Reuter reported.

WAFA said the Israelis unleashed a "hellish rain" of bombs on both military and civilian areas. For most of the day, waves of Israeli bombers and shelling from land- and sea-based gunners left the city enveloped in thick smoke.

Advancing Israeli tanks and armored vehicles gained complete control of the Beirut airport, about four miles south of the center of the city, and fought their way several hundred yards beyond it. Military analysts here said they believed that the Israeli objective was not to seize land or launch an all-out onslaught but rather to demonstrate the force of Israeli firepower.

In the fighting around the airport, Palestinian, Lebanese Shiite Moslem militiamen and Syrian troops contained the Israeli advance at some points, in many cases with shoulder-held, rocket-propelled grenade launchers.

Israeli shelling began shortly after 3 a.m. 9 p.m. Saturday, EDT as artillery and naval gunfire alternated between targets in the front lines or southern suburbs and residential areas well within the city proper.

The Palestinians responded with hit-and-run salvos from truck-mounted, multiple rocket launchers that were fired, then moved on to other locations before the Israelis could pinpoint them.

Israeli warplanes began bombing runs at 6 a.m. According to Wafa, the planes had carried out as many as 170 sorties by mid-afternoon.

An American television team watched Israeli planes bomb a Syrian ammunition dump near the offices of the United Nations Cultural, Educational and Scientific Organization with pinpoint accuracy.

The gunboat and artillery shelling appeared less precise. Shells slammed into hotels and private apartment buildings near the Mediterranean coast that did not appear to be major Palestinian positions.

Today's bombardment appeared to render even more difficult the task of U.S. envoy Philip C. Habib, who this afternoon arranged the third cease-fire since he returned to Lebanon last Wednesday.

Saeb Salam, the former Lebanese prime minister and conduit between Habib and the Palestinians, told reporters of his frustrations in dealing with the American envoy.

Salam said he started telephoning Habib in the morning urging a new cease-fire. "It was fixed for 2 p.m., but Habib told me it was not for sure," Salam said. "Then I called back and he said 2:30, but not for sure, then for 3 p.m., then 3:30 p.m. and finally at 3:40 he said the cease-fire was set for 5 p.m."

"I felt Habib was embarrassed," said Salam, "especially every time I called him and America names."

Lebanese Foreign Minister Fuad Boutros, a Maronite Christian, had expressed hope only hours before the new attack that a crucial new meeting would take place today to work out details of the guerrillas' departure. Due to today's attack, the meeting was not held.

Despite the massive destruction, Lebanese and Palestinian officials and Habib were reported determined to get those talks under way Monday barring new military action.

PLO Leader Yasser Arafat, who met Salam in the early evening, was reported by the Lebanese politician to be "very angry" with the Israeli attacks, but proud of his troops' performance and "determined" to press ahead with the negotiations.

Despite the Israeli pounding, the Palestinians said they were pleased with the U.N. Security Council provision authorizing Secretary General Javier Perez de Cuellar to send U.N. observers to monitor the cease-fire. Palestinian officials have accused the United States of seeking to block any U.N. role in the conflict.

Meanwhile, most of the half-million residents of West Beirut spent another day in basements or other shelters, emerging only after the shooting stopped.

Within minutes of the cease-fire, the streets of the predominantly Moslem western sector were full of people trying to clean up.

Because of the lack of water, fires raged out of control all over the city. The worst destruction appeared to be in the suburbs and the Fakhani neighborhood where the PLO maintains many offices.

Two Israeli shells landed on Salam's annex office and more than two dozen others hit nearby. One landed on a mosque across the street. Two other mosques and a church were also reported damaged.

The destruction in residential areas prompted the International Committee of the Red Cross to issue a new appeal for the combatants to spare the civilian population and especially hospitals. The Red Cross reiterated earlier appeals for the Israelis to lift their blockade and restore water and power and permit relief supplies into West Beirut.

[In Paris, gunmen sprayed an empty parked car belonging to an Israeli Embassy employe in Paris with machine-gun fire, The Associated Press reported. No one was injured, police said.]