Ex-president Ferdinand Marcos has offered to give back $5 billion to the Philippines and to support the government of President Corazon Aquino if he is permitted to return there and be exempted from criminal prosecution, according to participants in the negotiations.

Marcos' representatives are now making a last-ditch effort to avert his indictment in the United States by promising American officials for the first time that he will promote "national reconciliation" in the Philippines if he is not charged.

"If there is no indictment, he will support the government of the Philippines. There will be national reconciliation," said Col. Arturo Aruiza, an aide to Marcos at his current home in Honolulu.

Representatives for Marcos have entered into negotiations with Philippine officials -- including President Aquino's brother Jose Cojuangco and Ambassador to the United States Emmanuel Pelaez -- seeking a deal in which Marcos would pay $5 billion in exchange for the right to return to his home province of Ilocos Norte, according to A. James Gregor, political science professor at the University of California, Berkeley.

Gregor, who has been in contact with the Marcos camp in Honolulu and U.S. officials in Washington, said that Marcos has agreed to stay out of political life, to keep out of Manila and to support Aquino. However, the former Philippine president has asked that his son, Ferdinand Marcos Jr., be permitted to run for political office, perhaps as governor of Ilocos Norte.

Marcos' offer of $5 billion, an amount so large it would rival the "mini-Marshall" plan of foreign aid the United States has proposed for the Philippines, was first proposed in early June. Although Pelaez reportedly opposed accepting the offer, he passed on the message from Washington to Manila.

Asked yesterday about the $5 billion offer, Pelaez, the Philippine ambassador, replied: "You have long ears . . . I'm not sure that I can reply to you. I'm not certain whether I can talk about it or not. I'd rather you didn't ask me."

In the past, estimates of the amount of money Marcos and his associates diverted have ranged from $1 billion to $10 billion. Marcos' offer of $5 billion in exchange for the right to return home was so high that it took Philippine officials by surprise.

"That's why the negotiations haven't been easy," Gregor said. " Everyone is saying, 'If he's got $5 billion, maybe he's got $40 billion."

Gregor, a conservative academic and the author of several books on the Philippines and Southeast Asia, has ties to both the Marcos camp in Honolulu and to U.S. policy makers in Washington. He said that he has not been a direct party to the negotiations over Marcos' future, but explained that "I sometimes carry messages back and forth."

"The former president doesn't want anyone to think he's buying his freedom," said another source close to Marcos who has taken part in the negotiations. "It's his love for the Philippines, his desire to go home. He wants to help restore the Philippine economy and if his personal resources can do that, he wants to do that."

In the United States, federal prosecutors in New York City have recommended that Marcos be indicted on fraud and conspiracy charges stemming from his alleged use of Philippine government funds to buy art and American real estate while concealing their ownership. In the Philippines, he faces both fraud charges and an intensive effort by the Aquino government to recover money he allegedly took from the Philippines.

It was not clear what effect, if any, an agreement between Marcos and Manila would have on the question of a U.S. indictment. However, one Marcos representative who asked not to be identified said it is their hope that American authorities "will stall the indictment until they see what's happening."

Another source who asked not to be named said public disclosure of the "incredibly delicate" talks is likely to force Aquino to decide immediately whether to accept the Marcos offer.

In recent weeks, representatives for Marcos have been carrying on negotiations with two governments, the United States and the Philippines, in an effort to settle his future, avoid criminal prosecution and, if possible, secure his return to his homeland.

In the two years since the revolution in which Marcos fled to Honolulu, Aquino has said repeatedly that he could not return. Recently, however, she eased her position slightly and said Marcos might be permitted to return to his homeland if he were willing to stand trial there.

If Marcos were allowed to return to the Philippines, he would apparently be free of worries that he might be forced to stand trial in the United States. There is no extradition treaty.

When Secretary of State George P. Shultz visited Manila two weeks ago, he was greeted by more than a thousand pro-Marcos demonstrators carrying signs such as "U.S. Bring Back Marcos" and "President Marcos, Man of the Masses."

According to Gregor, the negotiations over Marcos' return and the huge cash payment began in early June, when representatives of Marcos first approached the office of Rep. Stephen Solarz (D-N.Y.), chairman of the House Foreign Affairs Committee's subcommittee on Asia, to sound him out on the idea. Gregor said Solarz's office rebuffed the overture.

A Solarz aide said he told a Marcos representative, public relations executive Jay Hoffman of Los Angeles, that he should make his offer through official channels of the Philippine government. The Solarz aide said he was skeptical of the entire effort. "Does Marcos really have $5 billion in liquid amounts?" he asked.

Marcos' representatives then approached others, including Allen Weinstein of the Center for Democracy in Washington and, eventually, Ambassador Pelaez and Deputy Chief of Mission Raul Rabe of the Philippine Embassy. According to Gregor and another source, in at least some cases, the specific amount of $5 billion was mentioned.

"I can't confirm or deny anything," Weinstein said yesterday.

Gregor said the Philippine ambassador was personally opposed to the idea. "He felt it would be like selling a principle for cash," Gregor said. Nevertheless, Gregor said, Marcos' offer of $5 billion "was conveyed by Ambassador Pelaez to the Philippines by diplomatic wire."

In recent months, Aquino has been making new intensive efforts to recover some of Marcos' wealth and bring it back to her impoverished country. A few weeks ago, she traveled to Switzerland to discuss with banking officials there the possibility of obtaining funds from Swiss bank accounts controlled by the Marcoses.

Marcos' offer to turn over $5 billion offered the Philippine government a chance to get back a huge amount of money quickly and with little effort. It was apparently taken seriously enough in Manila to prompt detailed talks concerning the proposal, and Gregor said Cojuangco, the president's brother, was authorized to come to Honolulu for further talks.

It could not be ascertained whether Cojuangco ever came to the United States. While refusing to confirm or deny the $5 billion offer, Ambassador Pelaez said last night there had been "no negotiations" concerning Marcos' return.