Ringed with armored personnel carriers and coils of barbed wire and emblazoned with blue-and-white Israeli flags, the cavernous Lebanese government regional office here hums with the noises of a busy bureaucracy transplanted from Israel.

Now the regional occupation office, which the Israeli Army calls "headquarters for aid to the civil population of Lebanon," the operation eerily resembles the occupation headquarters in Beit El, near the West Bank town of Ramallah.

Israeli critics of the war in Lebanon, voicing skepticism of Prime Minister Menachem Begin's promise to withdraw his Army once Palestinian guerrillas and the Syrian Army leave, have begun to refer to southern Lebanon as the "North Bank."

At the office here, typewriters chatter ceaselessly and file drawers bang open and shut as clerks scurry from office to office laden with the paper that fuels the engine of government. Anxious-looking Lebanese, seeking permits for everything from travel to the next town to building a new house, sit on long wooden benches along a drab green corridor, nervously fingering worn passports. A bored Israeli Army private absently shuffles through papers and waves earnest-looking officers into the inner sanctum of the commander.

Inside, Col. Shaul Nurel, head of the assistance section of the Israeli Civil Administration of southern Lebanon, reads the official orders and memos that clutter his desk, and answers his two telephones, alternately speaking in Hebrew and Arabic. It is another day with not enough hours, and the work keeps piling up.

Across town, Khalim Fayad, regional governor of the Lebanese central government, sits in a borrowed office at the University of Lebanon. His desk is as bare as the shelves behind him and, except for two uniformed guards, the waiting room outside is empty.

Fayad was displaced when the Israeli Army moved into the regional government building, and with a mixture of grudging admiration and vague worry, he has watched the Israeli Army almost overnight assemble a vast and complex occupation administration that has signs of being around for a while.

What gnaws at the back of Fayad's mind is that the Israelis have done it with the kind of studied efficiency that comes only with practice, and that time may slowly erode their declared intention to allow the Lebanese to run their own lives as much as possible.

"We know that in the West Bank and the Gaza Strip they have done many things. They have dismissed mayors and removed municipal counsels. But we are against any such developments here. We stand firmly . . . , this country is sovereign, and we want this occupation to come to an end so that the Lebanese can take care of themselves," Fayad said.

To a visitor who for four years observed at close hand the Israeli occupation apparatus in the West Bank, the similarities in Lebanon are striking.

Many of the faces are familiar, including that of Nurel, who for 14 years worked in the West Bank, Gaza Strip and Sinai Peninsula. Organizational charts on the walls here are almost identical to those in the West Bank headquarters, with departments for health, welfare, industry and trade, agriculture, transportation and other functions of civil administrations.

Most of the Army officers and civilian employes here were either drawn from the West Bank occupation headquarters or have had experience there, Nurel said, and many procedures here were simply moved from Beit El.

Nurel says there are also fundamental differences. "The structure differs in that in the West Bank, the civil administration is engaged in actually doing things. It builds schools and hospitals on its own, and initiates other projects on its own. Here, we are simply assisting the local inhabitants. They are putting their lives in order, and all we are doing is making it easier for them," Nurel said.

He added, "I consider the population here, compared to Judea and Samaria the Biblical names for the West Bank , to be basically friendly. We do not have the same kind of relationship."

On some aspects of the occupation, Nurel and Fayad are in basic agreement. Fayad, for example, concedes that most of the rebuilding of war-shattered southern Lebanon is being left to the Lebanese with a minimum of Israeli interference.

"There is no doubt that they have a lot of experience in the occupation business, but they admitted themselves that they were surprised to see in Sidon that the Lebanese could, in a very short time, clean up the debris and restore the essential services. We did it ourselves, and we did it very efficiently," Fayad said. He estimated that in the Sidon region alone, the Israeli invasion caused about $200 million in damage, including crops lost because of neglect.

The governor said the resiliency, ingrained after nearly a decade of violence, would sustain them through the rebuilding period -- although he added that the Israeli efforts to help were appreciated.

However, Fayad said, there have been incipient signs of Israeli interference in day-to-day decisions of the central Lebanese government, and the beginning of Israeli diktats that smack more of lasting occupation rule than benevolent assistance.

In some cases, officials of the central government have dared push back.

When the Israelis opened a Sidon branch of El Al, Israel's national airlines, to sell tickets to Lebanese traveling abroad by way of Israel, the Lebanese Ministry of Tourism launched a formal complaint and suspended the license of the Sidon tourism council because Lebanese law prohibits commerce with Israel, Fayad said.

Similarly, when Israel began exporting goods to Lebanon without consulting the central government on customs control, the government complained.

"Of course there are things they do without our approval, because they are in a position to do what they want," Fayad said. Every day, he added, Lebanese law is being violated when Israeli forces arrest local inhabitants, notwithstanding the fact that since the 1976 civil war the law in southern Lebanon was the rule of the gun and that the central government was helpless in the midst of numerous and often rival guerrilla organizations.

Fayad, who was not at Sidon when the invasion began, returned three weeks later to find the occupation command firmly installed in his offices. Assured by the Israelis that he would soon get his offices back, the governor moved to the university, where, he says, he cannot function efficiently because all of the official records remain in the regional headquarters.

"We are still waiting to see those offices evacuated," said Fayad, adding that the Israelis have begun to bypass him and deal directly with some of the central government agencies that remain in the building.

A notable exception to the pervasive Israeli occupation presence throughout most of southern Lebanon is Nabatiyah, a former Palestine Liberation Organization stronghold to which thousands of Lebanese residents began returning after the second week of the war.

There, the Israeli command does not even maintain an occupation headquarters and it is rare to see an Israeli soldier. Predominantly Shiite Moslem and generally sympathetic to the Israeli objectives in Lebanon, Nabatiyah residents seemed more concerned about restoring economic links to Beirut than the occupation of their country.

Mohammed Ali Randour, an importer and citrus farmer who is now filling the mayoral post for his aging father, said, "You are talking now to a pure Lebanese. We did not invite the Israelis here, but life is functioning better. Our police force is conducting its job. We are not having the interference a lot of people expected."

Apart from the social and economic problems created by an influx of refugees from Beirut, Randour said, Nabatiyah is functioning more smoothly than it has in years. But, he emphasized, residents want the Israelis to leave and the central government to assume authority.

"We have had very hard times, and we have learned not to believe anyone. We hear the Israeli declarations that they intend to leave, but we will only thank them when they are actually gone. I can't cash promises," Randour said.