A team of U.S. experts is touring the war-battered remains of Beirut's port and its central business district, once the commercial heart of the Middle East, to see what the United States can so to aid in reconstruction.

The Americans yesterday went through the front line that divided Beirut during much of the 19-month conflict, which ended in November when an Arab peace force composed largely of Syrian troops entered the city.

It was the first time American government experts could see at first hand the extent of the devastation caused by the bitter fighting. Lebanese experts have estimated the damage from the fighting, which claimed more than 60,000 lives, at $3 billion.

The Americans are not the only ones to come here to survey Lebanon's needs. A French delegation is also studying ways its government can help and Lebanese Premier Selim Hoss is currently visiting Arab states to enlist their aid. According to press reports here, he wants the oil-rich Arab nations to set up a special commission to help the Lebanese government's development board.

The five-member U.S. survey team here is headed by Blaine Richardson, chairman of a task force on Lebanon of the Agency for International Development (AID). It includes experts on housing, seaport operations and general engineering.

The first stop on the tour was the burned and shell-pitted remains of the 26-story Holiday Inn, scene of bitter fighting a year ago between the Phalangist Party and its allies and the Palestinians and their lebanese allies.

Lebanese experts told George Lane, the U.S. charge D'affaires here, that the Holiday Inn and the neighboring Phoenicia Hotl are still "structurally sound" despite their external damage.

Reports last week by the Lebanese Hotel Owners' Association estimated losses to Beirut's hotels at between $50 million and $70 million. Only one of the city's luxury seaside hotels, the Vendome, escaped severe damage. It reopened New Year's Day.

Beirut's most famous hotel, the St. George, was gutted in the fighting and will probably need to be leveled and rebuilt. The Hilton Hotel, which was under construction when the fighting began, needs at least a year of reconstruction before it can take guests, according to the hotel association.

In the central city, the heart of Beirut's commercial district where banks from all over the world had their Middle East headquarters, streets have been swept clear of the rubble from the fighting.

The buildings, however, are in ruins. In newer ones, glass windows that make up most of their sides have been blown out and the supporting beams are twisted. Stone structures, built 80 to 100 years ago, appear to have survived the heavy shelling in better shape although heavy artillery had dug out hunks of stone and they are gutted inside, the buildings remain sturdy.

Some experts here have suggested bulldozing the entire 30-block commercial center into the Mediterranean Sea as landfill and starting from scratch with a new financial and business district.

"It would sure be a shame to tear them all down," said Charles Dean, an AID consultant on housing.

Further along, the city's main market section, the souk, with its myriad of tiny shops, is filled with rubble. The Buildings themselves, mostly old, appear to be sturdy, however.

In some areas shopkeepers have set up stalls on the streets and are back in business.

The port, once the busiest in the Middle East, reopened last month and so far 38 ships have docked there. Most of them, have been small coastal freighters.

While the main channel into the port is open and docks themselves have been cleared, warehouses, cranes and other port facilities have been almost totally destroyed. One port official told the U.S. experts that every spare part for port macinery has been looted and there is only one welding machine left to make repairs. All that is left in the spare-parts storage building is a pile of old motors that would not work.

A report for President Elias Sarkis by economist Munir Abu Fadel estimated last month that it would cost $500 million to rebuild the port. He estimated that close to $1 billion in goods were looted from port warehouses during the fighting.

The only major structure remaining standing is the grain silo, but the pneumatic machinary that sucks grain from the ships has been badly damaged.

Leganon, which imports most of the 400,000 tons of grain it consumes annually, needs the silo repaired quickly to avert shortages and end a continuing spiral in food costs.

Port officials estimated that it will take two months to clear the rubble from the area near the docks so new warehouses can be put up.

The U.S. survey team arrived here Sunday night and had an immediate meeting with Al Hoss, an economist, before he left on his tour of Arab nations. They expect to remain here all week for meetings with Lebanese officials, who have set up special task forces dealing with the port, housing and general relief.