Following are the main portions of the agreement being negotiated between the United States and Iran based on the four conditions announced Sept. 12, 1980, By Ayatollah Ruhollah Khomeini for release of the hostages. NONINTERFERENCE

Khomeini called for a statement from the United States that it would not interfere in the internal affairs of Iran.

The United States will deliver a formal declaration signed by the president in which the United States states its policy is to refrain from interfering from now on, either directly or indirectly, militarily or politically, in the internal affairs of the Islamic Republic of Iran. THE FROZEN ASSETS

Khomeini called for unfreezing Iran's assets inside and outside the United States and returning them immediately to Iranian control.

At the time of the hostage release, the United States will return to Iran $1.5 billion and 1.6 million ounces of gold (worth about $1 billion) that had been held in the Federal Reserve Bank of New York. Another $4 billion, which had been frozen in European branches of American commercial banks, will be turned over.

The United States will also guarantee delivery to iran of the remaining assets frozen in the United States as soon as an international claims commission is established. REMOVAL OF LEGAL CLAIMS

Khomeini called for nullifying all legal claims against Iran.

The United States and Iran will join in an international claims commission that will arbitrate bona fide debts to American individuals and companies and claims of Iranian nationals and institutions against the United States. Iran will establish a $1 billion fund to repay such debts or awards of the commission.

Iran will repay all outstanding loans by American commercial banks to the former government of the shah. It will also establish a $2 billion fund to pay off all other American bank loans to Iranian government entities and companies after such loans have been validated as legal by an international arbiter.

The United States will move in American courts, once the international claims commission is established, to bring about the cancellation as rapidly as possible of all judicial orders and attachments against the Iranian assets. It will also move to terminate all legal proceedings in American courts filed against Iran by U.S. nationals and companies.

The United States will also nullify all claims filed against Iran based on seizure of the embassy and taking of the hostages and will prohibit such claims from being filed against Iran in the future. RETURN OF THE SHAH'S ASSETS

Khomeini called for return of the fortune of the late shah and his family.

The United States will order a freeze of any assets in the United States of the shah and his close relatives. That same order will require the holders of such assets to report them to the U.S. Treasury. The attorney general will give notice that the United States recognizes all decrees and judgments of Iran nationalizing the property of the shah and his family. And the United States will aid Iran in obtaining and enforcing any judgment by an American court for the transfer of any such assets back to Iran.