"If you want to steal, steal a little cleverly, in a nice way. Only if you steal so much as to become rich overnight, you will be caught."

Mobutu Sese Seko, criticizing corruption in Zaire, May 20, 1976

If the current political turmoil in Zaire should force longtime ruler Mobutu Sese Seko to flee his presidential mansion, he has plenty of other places to call home: a lavish townhouse in Paris, a 32-room estate in Switzerland and a 16th-century castle in Spain.

Mobutu also should have no trouble paying for his departure. On past overseas trips, including official visits to Washington and a vacation in Disney World, he has often paid cash. When Mobutu made a brief stopover in Maine in 1987, for example, workers at the Bayview Inn in Bar Harbor watched one member of the Zairian entourage open a suitcase filled with cash and count out more than $50,000 to settle the bill, according to a spokeswoman for the inn.

Over his 26 years in power, while his country sank deeper into poverty and despair, Mobutu has become one of the world's wealthiest foreign leaders, with holdings not only in prime real estate but also in Swiss bank accounts and, reportedly, shares of some European businesses. Forbes magazine has listed him as one of the world's richest dictators.

A host of Zaire-watchers -- from diplomats to academics, from Zairian exiles to frequent critics on Capitol Hill -- is convinced that Mobutu has built that fortune by following his own advice to "steal a little cleverly."

To his many critics, Mobutu ranks alongside Ferdinand Marcos of the Philippines and Haiti's Jean-Claude Duvalier as a longtime despot who looted his nation's treasury to amass millions -- by some accounts, billions -- abroad. And following a week of rioting across Zaire that has forced the regime to share power with the opposition for the first time, these critics are hoping that Mobutu -- like Duvalier and Marcos before him -- is also about to fall.

On Sunday, Mobutu was forced to name longtime opposition leader Etienne Tshisekedi as prime minister in a move that seemed to mark the first real diminution of Mobutu's power in 26 years. But the two men now appear locked in a power struggle, with Tshisekedi calling Mobutu "a monster" and insisting he must go, and Mobutu still trying to cling to his office even with his credibility shattered and large segments of his military in open revolt because of poor conditions and no pay.

As the Zairian regime teeters, questions about Mobutu's wealth -- and how he obtained it -- become particularly intriguing, since for most of his rule he was the beneficiary of hundreds of millions of dollars in aid from Washington, where successive U.S. presidents have viewed him as a key African ally and anticommunist bulwark in a potentially unstable and inhospitable region. Mobutu came to power after a CIA-backed coup in 1965, following the assassination of nationalist leader Patrice Lumumba and a period of crisis and uncertainty in a country then seen as a flashpoint for Cold War confrontation in Africa.

The opposition has made Mobutu's wealth one of its principal issues, and some anti-Mobutu Zairians have said they are determined to try to track down what they believe to be his plundered loot. For his part, Mobutu this week refused to answer opposition charges that he was "a thief and a murderer," Reuter news agency reported from Kinshasa, the Zairian capital.

"History will judge me. . . . I shall remain silent," Mobutu told a group of supporters, according to Reuter.

The exact size of Mobutu's fortune is not known. Past estimates, from Zairian exiles, journalists and U.S. congressmen, range as high as $5 billion, while some U.S. government officials place the figure much lower -- in the tens of millions of dollars.

"He has established a kleptocracy to end all kleptocracies, and has set a new standard by which all future international thieves will have to be measured," said Rep. Stephen J. Solarz (D-N.Y.), a member of the House Foreign Affairs Africa subcommittee, who has estimated Mobutu's wealth in the billions. "He makes Marcos look like a piker by comparison."

Some U.S. diplomats with long experience in Zaire say that figure is greatly exaggerated -- "ridiculous," said one State Department official -- and they place Mobutu's wealth at between $50 million and $125 million.

"He's spending, he's not saving," an American diplomat said.

Mobutu's personal fortune may be reduced, said this diplomat and others, because of what they described as his practice of using money to buy off potential enemies. The diplomat and others said Mobutu buys villas for political rivals to co-opt them, awards trips to Europe as rewards and once imported 140 cars to use as "gifts" to university staffers who were complaining of low pay.

"Billions have been skimmed off, but it goes back to oil the machine," said a former CIA operative in Zaire who has kept business interests in the country.

Mobutu, in a 1988 interview with Africa News, said his European bank accounts hold "less than $50 million. What is that, after 22 years as head of state of such a big country?"

University of Wisconsin political scientist Crawford Young, a leading Zaire expert and author who has conducted extensive research into Mobutu's hidden wealth, said, "I don't doubt that some of his {Mobutu's} money goes back into the economy. But to say he only has $50 million is absurd."

The Zairian Embassy here, contacted for this story, said the ambassador was out of town and unavailable to comment, and that the embassy had no spokesman.

In Washington, Mobutu's most prominent supporter is international businessman Mamadi Diane, who describes himself as a friend of the Zairian president for the last nine years. Diane, in a telephone interview, said claims that Mobutu is a billionaire are exaggerated.

"People make a lot of allegations with no substantial proof," he said. "Nobody has been able to pinpoint anything except the homes. We in the U.S. were also saying that the shah {of Iran} had all those billions, but nobody ever found them. . . . We haven't seen the billion dollars of Marcos, we haven't seen the billion dollars of {ousted Panamanian strongman Manuel Antonio} Noriega.

"Mobutu, you have to say he has a very lavish lifestyle," Diane said. "A very, very lavish lifestyle. He has a grand style of living. He lives like an African chief." But Diane, too, said Mobutu gives away much of his money as a form of political largesse. "All day long he is giving," Diane said.

What is certain about Mobutu is that he has extensive real estate holdings. According to American diplomats, businessmen and members of Congress, Mobutu owns a 16th-century castle in Valencia, a luxurious townhouse on fashionable Avenue Foch in Paris, a 32-room residence in Lausanne, Switzerland, and estates in Italy, Portugal and several African capitals, including Abidjan, Ivory Coast, and Dakar, Senegal.

Mobutu also constructed a massive palace near his birthplace in far-northeastern Zaire at Gbadolite -- "a Versailles in the jungle," according to one Washington businessman who visited Mobutu there. A high-ranking Western diplomat who served in Zaire and visited the Gbadolite estate described it as "a kind of emerald city of Oz," complete with illuminated fountains and grand marble buildings. To reach the nearly inaccessable spot, Mobutu constructed a four-lane highway.

"I guess he likes homes," said Diane. "There isn't a single head of state in Africa who doesn't have three or four properties overseas." Diane said even Mubutu's most vocal Zairian opponents maintain homes in Europe.

Mobutu is also a big spender, particularly on his trips abroad. In the past, he has reportedly leased French Concordes for his trips, and his entourage usually includes about 100 aides. According to those who have handled past trips, one Mobutu aide is said to carry a suitcase filled with American dollars to settle hotel bills in cash.

Mobutu also was criticized before the House Africa subcommittee in 1982 for using a Zairian government plane to fly a 100-member entourage to Florida for a Disney World vacation. The estimated cost, according to then-chairman Rep. Howard Wolpe (D-Mich.), was $2 million.

It is unclear whether these trips were paid from Mobutu's own funds, Zairian government funds, or both. According to Zaire experts, the line between public and private funds often becomes murky when dealing with Mobutu.

Mobutu's lavish lifestyle is shared by some other African leaders -- the so-called "Big Men" who rule through repression while erecting ostentatious edifices in their own name. The tragedy of Zaire, say Mobutu's many critics, is that a once wealthy country rich with natural resources is now one of Africa's economic basket cases, virtually cut off from outside aid and suffering chronic shortages of everything from food to fuel.

Interviews with Zairian exiles, academics who specialize in Zaire, American diplomats, businessmen and journalists, and a former U.S. intelligence operative in Kinshasa reveal a complex longtime pattern in Mobutu's accumulation of wealth that includes:

Direct rake-offs from state-owned copper, cobalt and diamond mines. The country's giant state copper mining firm, Gecamines, and the state diamond mining firm, MIBA (Miniere de Bakwanga), were described by almost all of the sources as Mobutu's principal "cash cows." One U.S. aid official said, "It's corruption by taking revenues off the top of mineral resources."

Officials of both the World Bank and the U.S. Agency for International Development said that in 1988, about $400 million in revenues from Zaire's mineral exports disappeared and was never accounted for.

Nguza Karl-I-Bond, a onetime prime minister under Mobutu who is now a key opposition leader, testified before a U.S. congressional subcommittee in 1981 that earlier that year about 20,000 tons of copper worth $35 million had been sold privately, with the proceeds to go directly to Mobutu. Karl-I-Bond also told Congress that he knew of chartered aircraft hauling Zairian cobalt and diamonds for sale in Europe, with the money to be directly deposited into Mobutu's personal accounts.

Mobutu's direct control over Zaire's budget and central bank. This power has allowed him to divert hundreds of millions of dollars to his personal accounts or to the office of the president with a simple telephone call, U.S. diplomats and academics and Zairian exiles say. In 1979, a Zairian parliamentary commission openly accused Mobutu of illegally withdrawing Bank of Zaire funds for his own use over a two-year period. Later, in 1981, opposition leader Karl-I-Bond told the U.S. congressional subcommittee that Mobutu had recently ordered the bank to transfer $30 million to his personal bank account abroad.

Kickbacks from private businesses to Mobutu's circle. A Western diplomat who has served often in Zaire, once as ambassador, said, "Any business activity there has to include a percentage for the president."

Awarding of official contracts to cronies and family members. One of the main beneficiaries was Mobutu's late cousin, Litho Maboti -- known in Zaire as "Uncle Litho" -- who was able to use Mobutu's sweeping nationalization order of Nov. 30, 1973, called Zairianization, to build up a vast commercial and agricultural empire. One knowledgeable source, citing U.S. intelligence reports, said that when he died sometime in the 1980s, Litho was known to have about $1 billion in a Swiss bank account, but that could not be independently confirmed.

Mobutu also owns extensive land inside his country, accumulating a vast agricultural empire of coffee, tea and rubber plantations after expropriating the lands from their foreign owners under his 1973 Zairianization decree. Many of the seized lands were grouped together and managed under the Mobutu-owned conglomorate known as CELZA (Cultures et Elevages du Zaire).

Political scientist Young, in his 1985 book, "The Rise and Decline of the Zairian State," listed 14 plantations under CELZA employing some 25,000 workers -- making it by 1977 the third-largest employer in the country.

Citing U.S. Agriculture Department statistics, Young showed that CELZA-run plantations accounted for 23 percent of Zaire's cocoa bean production, 26 percent of its rubber and 15 percent of its tea.

According to Young, Mobutu also became the largest shareholder in the Banque du Kinshasa, where all state firms kept their accounts, as well as aquiring "indirect interests in the Zairian operations of ITT-Bell, Fiat, Gulf, Pan Am, Renault, Peugeot, Volkswagen and Unilever."

One example of Mobutu's penchant for setting up dummy companies for profit involves the Panamanian-registered firm Risnelia, which underwrote the gate for the 1974 heavyweight championship bout between Muhammad Ali and George Foreman -- the "Rumble in the Jungle."

According to Zaire scholar Stephen R. Weissman, in a 1974 article in the Nation magazine, the Risnelia company was wholly owned by Mobutu, who took personal control of the fight receipts.

According to Weissman, who interviewed the chairman of Risnelia, the Zairian government paid for the promotion of the fight with public funds, while Mobutu, through the office of the president, was estimated to take 42.5 percent of the fight's gross world receipts.