Edmond Naim, governor of Lebanon's Central Bank, is in the unique position of holding the purse strings of Lebanon's rival Christian and Moslem governments.

But he's a virtual prisoner in the bank building where he has lived for 19 months.Naim is a Maronite Catholic and the bank is in Moslem west Beirut. For him to leave could be dangerous.

The bank nonetheless is the only government institution that remains intact in Lebanon's 5-month-old political crisis, which has split the government, the army and every other department down the middle.

This has given the 70-year-old Naim unprecedented powers.

He said he bankrolls "the basic needs" of both governments, including food and fuel imports, to prevent a complete collapse of Lebanon's fractured public services.

In June 1987, when Prime Minister Rashid Karami was assassinated, Naim moved into the bank headquarters and has never left.

"It's more practical to live in the bank," he said in an interview in his plush sixth-floor office. "The streets aren't safe."

So now he lives in a two-room apartment atop the seven-story building, which is guarded by 50 policemen.

"I cook, wash my dishes, do my laundry and tend my plants there," Naim said.

His wife travels from the family home in Christian east Beirut "every two weeks for a weekend with me at the bank," Naim said.

Mrs. Naim, the former Hedda Hofer of Detroit, is a naturalized American of German descent.

The political crisis that began in September, when President Amin Gemayel's six-year term expired with no successor elected because of sectarian bickering, left Naim the man in the middle.

Gemayel named his Maronite army commander, Gen. Michel Aoun, to head a caretaker military Cabinet until a new president was elected.

Moslem and leftist factions refused to recognize Aoun and backed acting Premier Salim Hoss, a Sunni Moslem.

"The central bank finances the whole of Lebanon according to a formula of equality and in line with the population and area each of the governments rules," Naim said.

"Naim's the only official in this country behaving like a father to all the Lebanese," said Adnan Badra, a Sunni businessman in west Beirut.

Although Lebanon's economy is in peril after nearly 14 years of civil war, the Central Bank has gold reserves estimated at about $5 billion, with $800 million in foreign currency.

Naim, a lawyer and former university dean brought out of retirement in 1983 to run the bank, has shown that he will not be bullied by political pressure from either side.

Aoun has sought to impose his Christian government's authority on the bank. In December he closed the only crossing between east and west Beirut for 10 days after Naim allocated funds to Moslem army units.

Naim responded by providing the equivalent of $1 million dollars to the Moslem side to import flour because Aoun's blockade choked off supplies from the main warehouses in east Beirut.

Naim has also had to contend with a serious banking crisis.

The Al-Mashrek Bank went under in December because of a run by depositors panicked by reports it was overstretched through hefty investments.

The Central Bank, however, underwrote claims by its non-institutional depositors.