The U.S. government still is not sure where the 53 American hostages are being held in Iran and is keeping various military plans on the back burner until it finds out, officals said yesterday.

Carter administration executives are pressing the intelligence community to pinpoint the locations of the hostages, but the information is proving tough to dig out, sources said. Plans for another rescue and other military actions are still being explored by the Joint Chiefs of Staff, but they are being hampered by the lack of this key knowledge.

One reason the information about the hostages' wherabouts is proving so difficult to get, sources said is that the militants are acting largely as a law unto themselves rather than discussing their plans with their own and other governments. Such discussions would net more information than it is obtaining.

Although the militants said shortly after the April 24 rescue attempt that the hostages had been dispersed, some U.S. government officials trying to locate them doubt widespread dispersal.

The reason the militants must keep most of the hostages concentrated is to retain their tight grip and resulting political clout in the struggle for power with Iran. These U.S. officials believe most of the hostages are still in Tehran, although probably not at the American embassy compound.

The Iranian militants on April 27 said that all of the 50 hostagess held at the U.S. Embassy compound had been relocated, some going to the holy city of Qom south of the capital and others to the northwestern city of Tabriz.

The militants at that time did not discuss the three other American hostages in the Iranian Foreign Ministry in Tehran several blocks from the embassy.

The militants issued a statement that the hostages were being dispersed "so that we should not have to kill the spies in case of a repetition of the foolish acts by the American government." Militants have named eight provincial cities where they say the hostages have been relocated.

The Carter administration has refused to rule out another attempt to rescue the hostages, although the various plans cannot go forward until the Pentagon gets definite information on the hostages whereabouts.

The military options for Iran studied by the Joint Chiefs of Staff are wide-ranging. But sources said the focus has been on plans for actions that would not immediatly embroil other world powers. This rules out a blockade or mining of straits used to ship Iranian oil.

A show of U.S. military force in Iran proper and another attempt to rescue the hostages have failed to get top-level approval, sources said.

The April 24 rescue plan approved by President Carter, who was called "Golden Leaf" in the secret documents displayed by Iranian officals afterward, depended in part on advance help within Iran.

U.S. officals said yesterday that the Iranian government is aware of this and has launched what one called "a witch hunt" to find the collaborators.

Revolutionary Guards and clerics in Iran are bearing down especially hard on the Iranian military in this search, sources said yesterday.

In contrast to the scanty intelligence on the whereabouts of American hostages, officals said Washington now has hard evidence about these post-raid investigations.

Details of the rescue plan, many of which were contained in the American documents left in Iran and displayed to news people inTehran, indicates U.S. commanders felt certain they could penetrate Iran's air space extensively without setting off alarms.

THIS CONFIDENCE SUGGESTSS DETAILED KNOWLEDGE OF THE STATES OF iran's defences during the nights of the rescue attempt.