A new Iranian proposal for resolving the 14-month-old hostage crisis, under intensive study by American officials and bankers in Washington, New York, London and Algiers last night, hinges on the return to Iran of more than $4 billion in frozen assets being held by American banks in their European branches, according to U.S. officials.

These officials refused to predict whether the Iranian plan can be accepted, but a senior administration sorce said that "in principle it is not unreasonable" and that its acceptance is within the realm of possibility.

As described by the sources, and suggested in an official statement broadcast late yesterday on Tehran radio, the release of the 52 Americans in the waning days of the Carter administration comes down, at the moment, to legal and technical issues between about a dozen major U.S. banks and the Central Bank of Iran.

The statement by Iran's Pars News Agency quoted chief hostage negotiator Behzad Nabavi as saying that the new proposal had been advanced because "U.S. banks have not made an acceptable move" to agree to the transfer of frozen Iranian assets to the central bank of a third country. Nabavi claimed that lthe U.S. government has already agreed, through Algerian intermediaries that such a transfer of the funds to a third country will take place before release of the hostages.

The Carter administration's determination to obtain the release of the hostages before it leaves office next Tuesday limited the amount of Iranian assets which it could deliver in the short time remaining. The administration previously gave Iran the date of Jan. 16 as the last practical moment for reaching an agreement which could be implemented by Jan. 20.

Nabavi, in his own twist on the Jan. 16 deadline, declared that the U.S. government "has an opportunity only up to the end of office hours tomorrow, Friday," to take "a really practical step in connection with the transfer of Iran's agreed deposits" or "the circumstances would radically be changed from the standpoint" of Iran. [Details on Page A19.]

Administration sources tended to discount Navabi's deadline, even while they reported that a maximum effort is being made to respond to Iran's proposal before today is over.

The latest and perhaps decisive sequence in the lengthy international drama began when the new Iranian proposal was delivered to Algerian diplomats in Tehran, who forwarded it to the senior American negotiating team that has been in the Algerian capital for more than a week.

The proposal, when relayed back to Washington, touched off an afternoon of meetings involving President Carter, Secretary of State Edmund S. Muskie and other high officials. The U.S. officials, in turn, were in touch with officials of the American banks which hold a large part of the Iranian governmental assets that were frozen under Carter's order on Nov. 14, 1979, 10 days after the seizure of the American Embassy in Tehran and its diplomatic personnel.

Trading Iran's captive money for thecaptive Americans has been a central feature of the United States negotiating strategy for many months.

The most recent U.S. offers to Iran involved the quick return of two categories of frozen Iranian assets in connection with release of all 52 of the Americans.

The first category is $1.5 billion in securities and 1.6 million ounces of gold, worth about $1 billion, which are held by the Federal Reserve Bank of New York. This would be placed in the hands of a third country when Iran agrees to the comprehensive deal, but would be transferred to Tehran only when the Americans are freed.

The second category -- and the focus of the latest proposal -- is the more than $4 billion in Iranian deposits in the Eruopean branches of American banks. The U.S. government permitted the banks to use a portion of this frozen money to pay off outstanding loans which had been made to Iranian borrowers, many of them government borrowers, during the regime of the late former shah, Mahammad Reza Pahlavi.

Roughly $1 billion in Iranian funds were "offset" in this way against the bank loans.

The Carter administration had proposed that the American banks and the Iranian Central Bank resolve the matter by a restoring their previous relationships and reinstating or paying off the loans. This would permit the asets flow back to Iran after they were unfrozen by presidential order.

Meetings between representatives of Iran's Central Bank and lawyers for the American institutions, over the past week in London, Paris and NEW york, failed to resolve the difficult questions involved. A sticking point for the banks is their concern about the previous loans, which are now deemed to be both risky and unsecured in the wake of the Iranian revolution.

These fears were increased last month when Iran proposed to "review" the old loans as part of a process of settling its accounts with the U.S. banks. This raisedc concern that some of the loans might be deemed illegal, and thuse not repaid.

gThe new Iranian proposal, accordingto U.S. sources, is a different way of dealing with the problem. It is reported to be based on a suggestion made almost a year ago by the Iranian Central Bank. According to one account, Iran at that time proposed an arbitrator to examine the loans and settle any other differences with the banks holding Iran's money.

If the matter can be resolved, this Iranian money in overseas banks, like the assets in the hands of the New York Federal Reserve, will be transferred to a third country when Tehran agrees to a deal, but will be released to Iran only when the hostages are freed.

The two categories of funds to be quickly returned represent only about half the total sum of frozen Iranian assets under the control of United States, according to sources on both sides. It appears that a transfer of the balance would await further legal steps, following the return of the hostages, under an agreement between the two countries.

Washington sources said the new Iranian proposals also include a few other "small points" of difference with the latest U.S. plan, but these are not expected to be a serious stumbling block to an agreement.

Asked if the Iranian proposal received yesterday is a positive or negative development toward the release of the Americans, an informed American official responded that it is "up, but not over the top."

The remaining issues under discussion in the indirect negotiations with Iran apparently do not include the return of the wealth of the late shah and his relatives.Muskie, addressing a foreign affairs forum at the National Theater before the latest proposal was received yesterday, said that while the United States has not been told explicitly that conflicting positions on the shah's wealth have been resolved, this has not been at issue in recent exchanges in Iran.

Tehran appears to have dropped its demand for a $10 billion cash guarantee that it will receive the Pahlavi fortune in the United States, a fortune which U.S. officials doubts exists. The United States has proposed instead to freeze any Pahlavi assets still in this country, and assist the Iranian government in pursuing its claim to those funds in American courts.