In addition to moving vast amounts of weaponry into Lebanon, Israel also is sending in experienced civilian and military administrators from the West Bank and Gaza Strip to enable it to to run civilian affairs in the southern portion of the country for a long period if necessary, according to Israeli military sources.

The Israeli Army has appointed "military coordinators" for the captured cities of Tyre and Sidon to care for the thousands of Lebanese civilians whose lives have been thrown into turmoil by the Israeli sweep into the Arab country on its northern border.

To aid the military coordinators, the Israeli Defense Ministry is transferring administrative and security specialists from territories occupied by Israel since the 1967 Middle East war, the Israeli military sources said. Their jobs include control of the civilian population and searches for guerrillas in hiding, as well as the organization of such civilian facilities as water and food distribution.

"Since 1967, we have had a lot of experience in this field, and we're putting it to use," a source from the military command said.

The Israeli occupation effort in Lebanon, observed during a drive Thursday from the border to Sidon and back and described by Israeli military sources, reflects a determination to keep Israeli troops in Lebanon to pursue and destroy Palestinian guerrillas during what are expected to be protracted diplomatic contacts for a settlement.

"We will not leave one stone unturned," the Israeli chief of staff, Maj. Gen. Rafael Eitan, said last night. "It may take a long time."

Israeli military intelligence estimates that between 15,000 and 16,000 armed guerrillas were in Lebanon before last Sunday's invasion. About 6,000 of the guerrillas were believed to be in Beirut, which Israeli forces had bombarded but had not entered. These figures tally with the most reliable estimates in Beirut.

Since Sunday, when the operation began, the Israeli Army has announced it has killed about 500 guerrillas, whom it always refers to as "terrorists." This figure presumably has grown in the most recent fighting.

Several thousand guerrillas are believed to be still in the area under Israeli control, in hiding or posing as civilians in an attempt to escape capture. Others have fled northward to join their comrades in Beirut, Israeli military sources said.

To root out the guerrillas remaining in the occupied portion of Lebanon, Israeli forces are conducting what would be described in English as "mopping-up operations." The Hebrew word Israeli officers use to describe the operations means "purification."

Israeli administrators from the West Bank have long years of experience doing this sort of work, the sources said. They conducted similar searches after Israel captured territory from Jordan that Palestinian guerrillas used to mount infiltration raids across the Jordan River in 1968 and 1969, often hiding in hills and caves around the West Bank similar to those in Lebanon.

Israeli soldiers, backed by tanks and armored personnel carriers, man frequent checkpoints along most of the shell-pocked roads that traverse southern Lebanon. They stop cars, many flying white flags from antennas, and demand Lebanese identity cards of all civilians. Unfriendly interrogation awaits those who do not have them.

Hillsides bristle with radio relay equipment. The skeleton of a military communications network covers the occupied territory--stretching from the border to a line eastward from the southern Beirut suburbs to Israeli positions in eastern Lebanon just south of the main Beirut-to-Damascus highway.

The grounds of the Zahrani oil refinery just outside Sidon have been turned into a giant parking lot and repair facility for the hundreds of armored vehicles that have swept north over the craggy southern Lebanese hills and through their ochre stone villages.

Although Israel refuses to divulge figures on its forces, so much armored equipment and military trucks have been plying the Lebanese highways in recent days that they have backed up, creating long traffic jams.

The heavy traffic by tracked vehicles, including U.S. and Israeli-made tanks and self-propelled cannons, has chewed up a road system already in dismal repair after seven years of Lebanese conflict and Israeli bombing and shelling.

Both coastal towns were heavily damaged during the Israeli assaults in which they were captured from Palestine Liberation Organization guerrillas who had been administering them through sympathetic local Lebanese civil officers and Moslem militias.

Israel has not disclosed casualty figures among the civilians. The Lebanese Red Cross, according to radio reports from Lebanon, estimated that 1,000 persons were killed and 3,000 wounded in the battle for Sidon and the Israeli bombardment and shelling that preceded it.

A visit to Sidon on Thursday showed the once-lively port city had suffered widespread damage to apartment and office buildings. Those residents who had not fled were without food, water or medicine. Foreign journalists who visited Tyre reported similar conditions there.