Former president Ferdinand Marcos and his wife, Imelda, siphoned more than $100 million out of the Philippines in embezzled and extorted funds, and then conspired with Saudi financier Adnan Khashoggi to try to save their assets after fleeing to the United States, a federal grand jury in New York charged yesterday.

The 79-page, six-count indictment alleges that the Marcoses and others, beginning in 1972, engaged in a broad racketeering scheme to steal millions of dollars in Philippine government funds; demand "substantial bribes, kickbacks and gratuities" in cash or stock, and convert the illegally acquired funds from Philippine pesos into U.S. dollars for investment in this country.

The indictment also charges that the Marcoses -- after leaving the Philippines for Hawaii in February 1986 -- conspired with Khashoggi to conceal their ownership of four New York office buildings. It alleges that they obstructed justice by creating false, backdated documents purporting to show that the properties had been sold to Khashoggi in order to circumvent a federal court order blocking the Marcoses from transferring their assets.

"Throughout our history, the principle that no person is above or beyond the law has been etched into the foundation of our legal system," U.S. Attorney Rudolph W. Giuliani, whose office has been conducting the grand jury investigation since June 1986, said yesterday at a news conference in Manhattan called to announce the indictment.

The Marcoses, said James M. Fox, director of the Federal Bureau of Investigation's New York Field Office, used "their position of trust to turn the Philippines' treasury into their own treasure."

As outlined in the indictment, the Marcoses, while reporting total after-tax income in 1965-84 of slightly more than $1 million, concealed millions more in stolen and illegally obtained money in numbered or other hidden bank accounts in the Philippines, Switzerland, Hong Kong, the United States and elsewhere, and secretly bought real estate and personal items worth millions.

The indictment alleges that in 1981-83, the Marcoses transferred $103 million in illegally obtained funds into the United States and purchased the four Manhattan office buildings, and then defrauded Citibank and Security Pacific National Bank of more than $165 million in the transactions and their financing.

The Marcoses could be forced under U.S. racketeering laws to forfeit the four New York buildings, foreign bank accounts and other holdings. Giuliani said this "could add up to a quarter of a billion dollars or more."

The government also seeks forfeiture of Khashoggi's Olympic Towers condominium in Manhattan, his bank accounts and any interest he holds in the four buildings.

Attorney General Dick Thornburgh in a statement said federal racketeering laws permit him to authorize the return of seized property to the Philippine government, which has filed a separate civil suit seeking to recover Marcos' assets.

White House spokesman Marlin Fitzwater, told reporters at a campaign stop in Bowling Green, Ky., that President Reagan "regrets the need for this" but that the Justice Department had "a very strong case" against Marcos.

Fitzwater said Reagan had been advised by State Department and national security officials "that there were no foreign policy considerations to prevent indictment" and concluded that the Justice Department should "do what it thought was right."

Fitzwater said Reagan is "saddened because Marcos was a friend, and a friend of this country, but he recognizes that the justice system must go forward."

The Philippine government hailed the indictment. "Given the pattern of corruption and abuse that marked the 20-year Marcos regime in the Philippines, we are not surprised at this indictment," Severina Rivera, general counsel of the Presidential Commission on Good Government, which cooperated in the investigation, said in a statement.

She said the indictment will send a "powerful message" to "dictators around the world who hold themselves above the law, loot their country, and abuse public trust for private gain that they can no longer find safe haven in the U.S. . . . "

In Honolulu, attorney Richard A. Hibey, emerging after a 35-minute session with the couple in their Honolulu Hills residence, said they had rejected a nonnegotiable "drop dead deal" with the Justice Department. "They vigorously will defend the charges that have been laid against them. We are confident that the charges against them are false and will be shown to be such," Hibey said.

He said Marcos, 71, may be too frail to withstand the rigors of a long criminal trial and criticized the United States for rejecting Marcos' offer of a "global settlement" of all disputes with the United States and the Philippine government. He said Marcos still seeks such a settlement, but the United States "flatly rejected" this. "There was absolutely no inclination, no disposition at all by the U.S. government to explore this possibility," Hibey said.

Hibey said the Justice Department on Tuesday gave Marcos and his wife, who is 59, until 5 p.m. Thursday to agree to plead guilty yesterday in New York to charges of racketeering, which are punishable by 20 years in prison.

Hibey said Marcos tried to communicate with the "highest levels" of the U.S. government and received a hand-delivered State Department letter Thursday night, but he indicated the U.S. position had not changed.

Hibey said he was given only "very limited opportunity" to offer a settlement, in a Tuesday meeting with Justice officials and in a subsequent memo.

Contrary to reports that Marcos was promised he would not be imprisoned if he pleaded guilty, Hibey said the Justice Department offered only to remain silent at sentencing.

Hibey said the U.S. deal would have required the Marcoses to testify and cooperate against other codefendants, including members of their family. Hibey said Marcos may appear for arraignment by Oct. 31 at U.S. District Ccurt in Honolulu rather than travel to New York, as ordered by U.S. District Judge John Keenan.

Marcos has offered up to $5 billion in exchange for safe conduct home to the Philippines and a promise that he would not be prosecuted.

Khashoggi's lawyer, Robert Morvillo, in a statement said his client "vehemently denies that he knowingly violated any United States law in connection with any dealings" with the Marcoses.

Khashoggi, 53, resides in France; a U.S.-French extradition treaty covers the crimes with which he is charged.

Officials at the State Department and elsewhere had expressed concern about setting a precedent in the Marcos case that could complicate efforts to convince other foreign leaders to leave office.

Fitzwater and other administration officials emphasized that Marcos was being prosecuted for activities allegedly committed since coming to the United States. "Had Marcos behaved himself, he probably wouldn't have been indicted," Fitzwater said.

"This indictment includes allegations of serious illegal conduct engaged in subsequent to the Marcoses arrival in the United States," Thornburgh said, that defrauded ". . . United States financial institutions as well as the United States judicial system."

Administration sources termed it a "take-it-or-leave-it" offer and said that in return for forfeiting millions of dollars of assets and pleading guilty to racketeering, Marcos would have received a recommendation from Giuliani that he not be imprisoned.

The indictment also charges Marcos associates Bienvenido Tantoco Sr., former Philippine ambassador to the Vatican, and his wife, Gliceria, former head of the Rustans Department Store in the Philippines, who allegedly helped hide the Marcoses' ownership in the New York properties.

The indictment charges that Gliceria Tantoco and the Marcoses paid nearly $6 million for the Samuels Collection, the contents of a Park Avenue apartment, and engaged in racketeering by interstate transport of stolen funds and art works.

The indictment also charges the Los Angeles-based California Overseas Bank; its chairman, Roberto S. Benedicto, and former president Rodolfo T. Aranbulo with helping the Marcoses wire funds to buy the properties.

The Marcoses and the others were charged with two counts under the Racketeer Influenced and Corrupt Organizations (RICO) law, and one count each of mail fraud and obstruction of justice. If convicted, they face a maximum of 50 years in prison and fines totaling $1 million. Khashoggi was charged with two additional counts of obstruction of justice.

There was speculation in the Philippines that the decision to proceed with the indictment was linked to an accord reached this week on two strategic U.S. military bases in the Philippines.

A knowledgeable State Department official said the question of Marcos' indictment never came up during the base talks. But Hibey called the bases' agreement and the indictment a coincidence "too strong to ignore."

He added that Marcos' willingness to appear in court does not mean he is dropping claims of immunity from prosecution as a former head of state. He said Marcos was brought to Hawaii against his will after leaving Malacanang Palace on the understanding he would go to his home province of Ilocos Norte.

He said the Philippine people know the Marcoses are victims of "a political vendetta," and that the government of Corazon Aquino is "leaving {itself} in a colonial position, leaving it up to the United States to . . . force this man and his wife into a court here in the United States."

Asked if he felt Reagan had betrayed Marcos, Hibey said: "President Reagan was responsible for his being brought to the United States, and his fate is in every practical respect in the hands of Ronald Reagan."

Contributing to this report were staff writers Lou Cannon, Don Oberdorfer and Joe Pichirallo in Washington, Keith Richburg in Manila and special correspondents Marianne Yen in New York and Walter Wright in Honolulu.