Richard N. Frye, Aga Khan Professor of Iranian who returned from Teheran on Monday, said yesterday the White House letter sent to Iranian President Abolhassan Bani-Sadr is a positive step toward resolving the hostage situation, but Frye added that he does not expect the hostages to be released soon.

Frye said numerous messages have been sent to Bani-Sadr by the Carter Administration, but the latest note is "presumably conciliatory."

The Iranian newspaper Bamdad released the news of the letter on Saturday with the headline "Carter Message Shakes Everyone," Frye said.

"The people in Teheran that I talked to were very glad and seemed very much relieved," he added.

One Iranian politician told Frye that the conciliatory approach "is what we have been urging for a very long time," Frye said.

The Iranian government hopes to have the police and the army replace the students controlling the American embassy, he said. Bani-Sadr needed an official apology from the United States to use against the militants who have held the U.S. Embassy in Tehran since November, Frye added.

"I don't think this will mean freedom for the hostages," Frye said. "However, it is getting them away from the militants."

Ali Banuazizi, editor of the Journal of Iranian Studies, said yesterday resolving the hostage crisis "is in the best interests of the Iranian people."

Banuazizi said he was optimistic about the hostages' release, but added that releasing the Americans cannot be discussed until the new Parliament meets following the elections in May.

Efforts to release the hostages are currently blocked by a power struggle between the moderates led by Bani-Sadr, the conservative clergy, and the militants, Banuazizi said.

"The moderates would like to resolve the hostage crisis and get on with rebuilding the country, but the conservatives wish to use the hostages to undermine Bani-Sadr's strength," Banuazizi said