Palestinian guerrillas attacked French U.N. troops in three bloody clashes in southern Lebanon yesterday that left at least one French soldier dead, eight wounded and five missing.

One of those wounded was Col. Jean-Germain Salvan, commander of the French U.N. forces. Salvan, whose jeep was ambushed, was reported in good condition in a Beirut hospital.

The series of clashes, all in the area of Tyre, was the most serious involving U.N. forces since the Security Council set up the peacekeeping operation five weeks ago following the Israeli invasion of southern Lebanon.

Mondy, three Senegalese U.N. troops were killed when the vehicle in which they were riding ran over a land mine. Earlier a Swedish and a French soldier had been killed.

Yesterday's fighting coincided with a move at the United Nations to increase the peacekeeping force in Lebanon from 4,000 to 6,000 troops.

According to official U.N. reports, yesterday's series of clashes began when a French U.N. vehicle was ambushed by Palestinian guerrillas two miles north of Tyre. One French soldier was wounded.

Fifteen minutes later, Palestinian guerrillas opened fire on the Tyre barracks of the French U.N. forces, and the two sides battled for more than a half hour. A French soldier was killed and five were injured.

Shortly after the attack on the barracks was repulsed, a French armored car was found destroyed north of Tyre and its three-man crew was missing.

Later, a Palestine Liberation Organization jeep carrying Salvan and a PLO liaison officer on an inspection ride was ambushed. Salvan was wounded and two French soldiers who were following him in a U.N. jeep were missing.

U.N. Secretary General Kurt Waldheim said he was "profoundly concerned" at the attacks, Washington Post correspondent Dusko Doder reported from the United Nations. Waldheim said he had been given a pledge of cooperation from PLO leader Yasser Arafat in efforts to calm the situation.

The attack followed three clashes several hours earlier between U.N. troops and Palestinian guerrillas trying to infiltrate past their lines into southern Lebanon.

One Palestinian was killed and two others wounded in a clash involving French troops near Tyre. Another Palestinian was killed in a clash with Senegalese soldiers. In the third incident, four guerrillas were captured by French forces after an exchange of gunfire near Tyre.

A previously unknown leftist group, calling itself the Popular Resistance Front for the Liberation of the South from Occupation and Reaction, accused the French of aggression in the earlier incidents and said it would use force against U.N. troops.

The Tyre hostilities coincided with a flareup between Syrian peacekeeping forces and radical Palestinian guerrilla groups in the port city of Sidon, 25 miles north of Tyre, leftist sources reported.

They said two guerrillas were killed in the clash on the outskirts of Sidon.

The Beirut-Sidon-Tyre highway was closed for normal traffic during the Syrian-radical clashes. Travelers arriving in Beirut from Tyre said they had to take a long detour to avoid hostilities in Sidon.

Syrians make up the bulk of a 30,000-man Arab League army that policies an almost 18-month-old civil war armistice in 80 percent of Lebanon.

There was no immediate official comment on the reported Sidon clashes from radical groups, the command of the Arab peacekeeping force or the Palestine Liberation Organization.

The U.N. peacekeeping force has its general headquarters at an American-owned oil refinery compound in Zahrani, two miles south of Sidon on the Mediterranean coast.