Honore M'Biye, a dapper 39-year-old man from Zaire, walked into the Washington offices of the World Bank sometime last February, and he was given a vacant office.

Employes on the 11th floor, home of the World Bank's affiliate organization, International Finance Corp., thought M'Biye (pronounced M-B-A) was a diplomat. He wore Italian suits, spoke flawless French, dropped the right names and carried himself with dignity. But as months went by, they noticed M'Biye never did any work. He arrived at 10 a.m., read books, made telephone calls and took leisurely two-hour lunches at Washington's finest French restaurants, IFC employes said.

In the meantime, the mysterious, soft-spoken foreigner had managed to obtain $6,000 in loans from two Washington banks, claiming to be a United Nations lawyer who earned $45,000 a year, court papers allege. He also purchased, a $13,000 BMW automobile, charged $1,000 worth of clothes at exclusive shops in town and had his name included in the 1980 World Bank telephone directory as a consultant.

By July, five months after taking over the spare, carpeted office, M'Biye aroused more than idle curiosity. IFC officials finally checked out M'Biye's credentials and discovered he was not a United Nations consultant, after all. In fact, M'Biye had been declared "persona non grata" by the United Nations security service in New York a year earlier after pulling a similar hoax and running up a $2,394 hotel bill, IFC officials learned.

M'Biye was asked to leave the World Bank building. After a scuffle with an IFC employe, he did so. Suddenly, a string of creditors began calling the IFC, saying one of its supposed employes, Honore M'Biye, had run up a sizable amount of debts.

On July 24, nattily dressed as usual in a dark suit and tie, M'Biye was summoned to The Hemisphere National Bank on Connecticut Avenue. After an interview with FBI agents, he was arrested and charged with three counts of making false statements to a bank, a felony offense.

On Monday, he will stand trial in U.S. District Court here. If convicted, he could face up to six years in jail and a $15,000 fine.

"We are terribly embarrassed by this case," said one IFC official in Washington. "To outsiders we look like fools. But should we now start a concentration camp?"

Honore M'Biye's odyssey from the high finance world of Europe to a cell in the D.C. Jail began several years ago, sources said last week. Former acquaintances, United Nations officials, law enforcement personnel and a trail of hapless victims portray M'Biye as a "con man extraordinaire," a grand impostor who was able to penetrate the international diplomatic scene with ease and perpetrate the sting with style.

The tall, bespectacled African, who also says he has a law degree from the Sorbonne, declined to be interviewed this week at the D.C. Jail. "I have many, many confusions." When asked specific questions, M'Biye lapsed into French, saying his lawyer would answer any questions.

James Craddock, M'Biye's court-appointetd attorney, said his client first came to Washington last November. "He charmed so many people," Craddock said.

He also conned them, according to the FBI and the victims.

M'Biye took an apartment at the Potomac Plaza Terraces, 730 24th St. NW, where be befriended a young Nigerian desk clerk. "He asked me for money. I gave it to him," said the clerk, who said that eventually M'Biye bilked him out of his life's savings.

M'Biye then moved to the Quality Inn on 16th Street, the FBI said, where he stayed for several weeks. A substantial hotel bill was never paid.

In April, he went to VOB Datsun in Rockville and picked out a new 321 BMW automatic with a price tag of $13,000.

"He really finagled us," company accountant Charlene Keener said yesterday. Keener said M'Biye gave VOB Datsun one check for $7,000 as a down payment. The check bounced, Keener said. "He told the general manager he had funds tied up in France. We tried to verify it. "When we called the World Bank, they said they knew him," Keener said. M'Biye sent the company another check for $7,000 that also bounced. Three months later, when M'Biye was arrested, the company repossessed the car. "He was a real character," Keener said yesterday.

"Despite the fact that he was not an employe, M'Biye had his own telephone extension and Room 203 on the 11th floor of the building at 1850 I St. N.W.

M'Biye traveled to Vienna and Rome for a week in June, telling friends he was on United Nations business and that the World Bank had paid his way. The Nigerian desk clerk, who wished to remain anonymous, said he received a transatlantic phone call from a desperate M'Biye. "He said he couldn't use his American Express card to get home unless I deposited $1,000 into his credit card account. It took the cash over to the American Express office here. When he got back, he gave me a check for $1,500," the desk clerk said. The check was worthless.

"He was a con person," the desk clerk said sadly. The clerk said he lent M'Biye a total of $2,500 -- his life's savings. "I think I have to blame myself for trying to be nice," he said.

Sometime that spring, M'Biye arranged to sublet an apartment at 3120 N St. in Georgetown from an International Monetary Fund employe who was transferred to Beirut. Elise Snyder, a Washington attorney, lived on the first floor of the small building. "He said he worked for UNIDO (United Nations International Development Organization)," Snyder said yesterday. "He was very low-key and dressed very nicely. We'd see each other on the stairs in the morning and say 'Bon jour'."

In late June, Snyder said, she came home to discover M'Biye packing his BMW, getting ready to leave. "He said he was leaving for two reasons. There was no place to park his car, and there was never any hot water in the morning. I felt badly about that," Snyder said yesterday.

In early July, M'Biye made arrangements to rent a house in Arlington. He purchased $150 worth of household items from the departing tenant, who said last week that M'Biye's check bounced.

Meanwhile, his welcome at the World Bank building was wearing thin. "He was a great nuisance," said one IFC employe who declined to be named. "He was an effective name dropper and seemed to be highly connected. People were afraid of him."

M'Biye did not receive any money from the IFC. "He borrowed money around town," the employe said. "He tried a few people at the IFC and also the African community in Washington. He misused his knowledge of international organizations. There's no way to avoid a man like him."

According to court papers, M'Biye tried to obtain a loan from the National Bank of Washington on Feb. 21, saying he was a lawyer employed by the United Nations, earning $3,500 a month. The loan was not approved.

Two months later, M'Biye went to the Hemisphere National Bank and told officials he was employed by the United Nations World Bank and earned $45,000 a year. Court papers include a copy of a letter, on IFC stationery, allegedly written by the organization's director of personnel to the bank's chief loan office, saying M'Biye was an assistant from the United Nations Industrial Development Organization (UNIDO) in Vienna and that his funds had not yet arrived in Washington.

"Thus, I would like to request that you establish for him a line of credit up to the maximum amount permissible by your bank in this situation," the letter read. M'Biye was given $5,000. According to law enforcement sources, the letter was written not by the director of personnel, but by M'Biye.

On or about June 16, the indictment states, M'Biye walked into a branch of the Riggs Natonal Bank, identified himself as a U.N. World Bank lawyer, and said he needed $1,000 for his trip overseas. Instead of a loan, the bank granted him overdraft privileges in that amount, sources said last week.

"This is an extraordinary and unusual case," said Sol Kuttner, adviser, U.S. Mission to the United Nations. "It's like a puzzle."

Kuttner said M'Biye was employed by the United Nations' affiliate Food and Agriculture Organization in Rome several years ago. In January 1979, he was assigned to a post in Haiti. According to Kuttner, M'Biye was fired after officials learned that he had left a trail of unpaid bills in Rome and had bounced checks in Haiti.

Kuttner also said M'Biye -- while supposedly working in Haiti -- travelled to New York that January, where he stayed at the Tudor Hotel, a block from the U.N., and ran up a bill of $2,934.

According to Neil Breen, assistant security chief at the U.N., M'Biye forged a director's name on a building pass that allowed him access to the U.N. "He passed himself off as a staff member of the U.S. Mission," Breen said.

Officials discovered the hoax, Kuttner said, after contacting Rome and Vienna. In February, Breen's office issued an alert, banning M'Biye from the building. The U.N. declined to prosecute, Kuttner said. According to several sources, the U.N. also paid M'Biye's hotel bill.

"This kind of thing could happen to any bureaucracy," said one IFC official, adding that the organization's security was somewhat lax. The official said the policy of checking credentials was relaxed several years ago after a bona fide foreign minister was ejected from the building after failing to produce identification. "We have a lot of visiting dignitaries and consultants coming in here all the time," said one IFC employe. "So it's not unusual to see unfamiliar faces."

"Honore's not a vicious person," said defense attorney Craddock, adding that his client has been treated kindly by the other inmates at the D.C. jail.

Court records state that M'Biye has no criminal record. He told police he had 16 years of education, listed his occupation as lawyer, and gave a Paris address as his residence for the past 10 years. If he does not receive a jail sentence, Craddock said, he will most likely be deported back to Zaire.

"It may be that people are fascinated by him," Craddock said. "He has a certain dignity to him." Said Elise Snyder, "I'm under the impression that he believes he is who he says he is."