Reagan administration officials said yesterday that documents brought to the United States by deposed Philippine president Ferdinand Marcos and his close associates detail not only the size of their fortunes but how they amassed them.

Within the sheaves of documents are "paper trails" of vast, world-wide holdings by Marcos and other prominent Filipinos who traveled to this country with him, including coconut magnate Eduardo Cojuangco, the officials said. The value of those properties dwarfs that of the jewels and 22 crates of freshly printed pesos that the Marcos party brought to Hawaii, the officials said.

Government officials in the Philippines have estimated the wealth of Marcos and his wife, Imelda, at $5 billion to $10 billion; one senior U.S. official yesterday said it appears that their wealth does reach into the billions of dollars.

Meanwhile, Australian officials said an unidentified party tried without success to hire Qantas Airways to carry 10 tons of gold bullion -- worth about $110 million -- out of Manila in the month before the Philippine election Feb. 7. Two Australian newspapers identified Marcos as the would-be shipper.

The documents aboard the Marcos plane include deeds, financial reports, contracts and legal agreements, according to the officials, who spoke on the condition that they not be identified. They do not contain valuations of the properties, however, and U.S. officials have made only a preliminary review of them.

Marcos earned a presidential salary of 100,000 pesos, about $4,700, but he reported considerable outside income from investments in the Philippines. Leaders of the new government of Corazon Aquino have charged that he bilked the economy and government while in office, secreting vast sums in overseas investments with hidden ownership.

Commenting on the controversy over Marcos' wealth, President Reagan said in a breakfast meeting with reporters yesterday that "the information I've always had was that he was a millionaire before he took office, and so there probably is some wealth that is his legitimately by way of investments over all these 20 years."

Reagan expressed concern about "undue harassment of any individual in this situation," but he also emphasized: "If there has been absolute wrongdoing, then there must be restitution." He said the issue should be left to the court system.

A senior State Department official said yesterday that delicate legal questions surround the Marcos documents -- Do they belong to the deposed president or does the new Manila government have a higher claim to them? He said the administration might resolve the issues through an interpleader process in which both sides would state their claims before a judge.

Another State Department official revealed that the administration last year considered assigning the Federal Bureau of Investigation to probe the extent of Marcos' holdings in the United States. However, the idea was dropped because of concern that if the investigation became public, the United States would be accused of trying to hasten Marcos' downfall.

There was also concern about FBI investigators being subpoenaed to testify before a congressional subcommittee investigating Marcos' wealth.

In Australia, informed sources said that a large Australian shipping firm was hired in early January to arrange for transporting 10 tons of gold bullion from Manila.

Officials said that in the month before the Philippine election, the transport firm "approached" Qantas Airways, Australia's national airline, about carrying the bullion on a Manila-to-Sydney flight.

Newspapers in Melbourne and Sydney reported that Marcos was the shipping firm's client, but Australian officials said they had not been able to identify the client.

A Quantas spokesman would only say, "We haven't carried any bullion from the Philippines."

The Aquino government is attempting to seize properties in the United States and elsewhere alleged to belong to Marcos, and leaders in Manila are pressing for access to the documents.

State Department spokesman Bernard Kalb said yesterday that the United States will provide the Central Bank of the Philippines with "a complete inventory" of the currency brought here by Marcos. A Customs Service spokesman last night promised "a fairly complete accounting" of the documents aboard the plane but said that it is not certain that the documents themselves will be surrendered.

Yesterday, a New York state judge extended until March 19 an order barring the sale of five properties valued at $350 million and alleged by the Aquino government to belong to the Marcoses.

Judge Elliott Wilk said he extended the order to give lawyers for the Philippine government time to compile documents uncovered in Manila and Hawaii that lawyers hope will prove the Marcoses' ownership.

"Documents are pouring in from the Philippines," said chief lawer Morton Stavis of the Center for Constitutional Rights, which is representing the Aquino government.

A lawyer for an offshore corporation that is the owner-of-record for one of the properties -- a Long Island estate named Lindenmere -- argued that the Aquino government is using "hearsay evidence, speculation and incompetent evidence" to portray his client, Ancor Holdings N.V., as a front for Imelda Marcos.

Customs Service inspectors in Hawaii, Alaska and California were watching yesterday for the arrival of Marcos' private yacht.

If the yacht is carrying valuables or cash, these would have to be declared upon arrival, Customs and State Department officials said.