Iran has proposed a two-stage financial settlement under which it would immediately repay its outstanding loans from American banks and establish a procedure for eventually repaying other loans made to Iranian institutions during the reign of the late shah, it was learned yesterday.

This portion of Iran's latest proposal, which was received in Washington Thursday afternoon, was directed at ending the last outstanding problem associated with the frozen Iranian assets -- the $6 billion in Iranian deposits frozen in the domestic and overseas branches of American banks.

It does not deal with other frozen assets, such as the gold and securities under the control of the Federal Reserve Bank, the weapons trust fund and spare parts in the hands of the Penatagon, and money owed to Iran by American oil companies.

Under Iran's plan, the president would unfreeze the entire $6 billion in bank deposits. From that amount, the Tehran government would use approximately $1 billion to pay off loans made directly to the prior government. Another $1 billion to $2 billion would be placed in escrow to cover another category of loans -- those the American banks had made to institutions and companies in which the late shah Mohammad Reza Pahlavi's government, or in some cases his family, had an interest.

American bankers, who had been negotiating with representatives of Iran's central bank for more than a week, were surprised by this latest proposal. Until now they had believed that Iran wanted to restore the deposit accounts and reestablish the loans by bringing interest and principal payments up to date.

This new approach would achieve two major objectives of the regime of Ayatollah Ruhollah Khomeini. It would wipe out all financial relationships between Tehran and the United States, and -- when the time comes to review the second category of loans -- the Tehran government would have a chance to renew charges taht the former shah and his family misused institutions to siphon off money for themselves. proposal, it could not be learned whether the method proposed by Tehran for handling the bank situation has been accepted.

One hypothesis about the rapidly unfolding events on the banking front held that Iran is being moved by financial problems relating to the war with Iraq and loss of some of its oil revenues. However, Iranian oil exports are reported to be running at 800,000 barrels a day, and one senior banker reported this week that, while Iran's refineries have been damaged, the pipelines and ports that link Iran with its world oil markets continue to operate fairly smoothly.

Thus, some sources say that political rather than economic factors may be the primary motives behind Tehran's stepped-up initiatives toward a settlement of the hostage question and even may spill over into efforts in the near future to end hostilities with Iraq.

American bankers looked on the immediate repayment of their loans to the Iran government as a positive development. The separate treatment being suggested for the remaining loans, however, raised the possibility that some of them might not be repaid.

The American bankers do not want to stand in the way of any hostage settlement, according to sources, but probably will not agree to the Iranian proposal without a presidential directive.

Without a presidential order, the banks could face stockholder suits should any of their loans not be repaid. With a presidential directive, they could sue the government for any losses.

A survey of the outstanding loans of the Chase Manhattan Bank of New York offers an illustration of the problem.

According to filings by Chase Manhattan in federal district court in New York, the bank had about $350 million in loans outstanding to Iranian borrowers as of Nov. 13, 1979, the day before the president's freeze on Iranian assets was instituted.

But only $50 million of those loans were directly to the government of Iran. This was the bank's portion of a $500 million loan made in 1977 by a syndicate headed by Chase Manhattan.

Among 37 other loans listed by Chase Manhattan, many are to institutions closely associated with the late shah's vast development plans. For example, $38 million was loaned to the National Petrochemical Co. of Iran, $19 million went to the Industrial Mining and Development Bank of Iran and $14 million went to the Agricultural Development Bank of Iran.

Smaller loans went to borrowers linked to the shah's family, such as the Kermanshah Sugar refinery, which is listed as receiving a $2.4 million loan.

Although the American banks are being portrayed as possible victims of the settlement to release the hostages, they actually are in an advantageous position -- and it was pressure from some banks at the time of the freeze and thereafter that put them in that position.

In the final years of the shah's government, American banks were rushing to participate in the boom economy that accompanied Iran's new oil wealth. Between 1976 and 1978 international banks, with U.S. institutions in the lead, extended more than $3 billion credit to Iranian borrowers.

The biggest single loan was the $500 million syndicated by Chase Manhattan.

After the Khomeini government came to power in early 1979 Chase Manhattan's prime role in Iran's economic affairs began to fade. The new government slowly began to place its valued oil revenues with other banks. It continued to keep all its payments on its loans up to date, including the one headed by Chase Manhattan.

After the hostages were seized on Nov. 4, 1979, the Iranian central bank continued to do international business as usual. On Nov. 14, however, with passions in the United States running high, President Carter announced a freeze on all Iranian assets held by American institutions both inside and outside the country.

At that point, Chase Manhattan declared Iran's loan in default, despite an order from Iran's central bank weeks before to use its funds on deposit to keep the payments up to date.

Chase Manhattan also took advantage of a U.S. Treasury regulation at the time of the freeze that permitted American banks to use frozen Iranian funds to "set off" or pay in full any loans in default. The Chase Manhattan loan default triggered the default on all Iranian loans, and all the American banks took the same advantage to "set off" their loans.

Because the banks had been given the opportunity to set off their outstanding loans, Treasury officials also added to their freeze regulations a provision that benefited American corporations and individuals who wanted to file lawsuits against Iran for money they claimed they were owed.

Normally, Iranian government money would be immune from such lawsuits. But the Treasury rule permitted claimants to go after the frozen funds, which they did with abandon. Some 300 suits have been filed, seeking billions of dollars.

Doing away with these claims has been another Iranian condition for release of the hostages.

That problem appears to be on the way to being solved through an agreement between the countries that would establish an international commission to arbitrate the claims. For its part, Iran has said it would set up a second $1 billion escrow account that would be used to pay awards to any successful claimant. Such an account, it was reported yesterday, was being established in Britain.