The United States has welcomed Iran's release on bail Tuesday of Haleh Esfandiari, an Iranian-American academic who has been jailed in Tehran since May. The State Department is urging immediate, unconditional, freedom for three other U.S. citizens detained by Iran. VOA's David Gollust reports from the State Department.

Both the White House and State Department are welcoming Esfandiari's release, which her boss and former U.S. Congressman Lee Hamilton says followed a personal appeal to Iran's Supreme Religious Leader, Ayatollah Ali Khamenei.

Esfandiari, who heads the Middle East program at Washington's Woodrow Wilson Center for Scholars, was visiting her mother when she was barred from leaving Iran and, after weeks of interrogation, arrested.

She was jailed in Tehran's notorious Evin prison, with prosecutors accusing her of harming Iran's national security and involvement in an alleged U.S. effort to topple the Islamic regime.

In a telephone conference call with Washington reporters, Hamilton, the Wilson Center's director, said he was unsure what prompted the release but said an important factor may have been the letter he recently sent to Ayatollah Khamenei appealing for Esfandiari's freedom.

Hamilton, a Democratic former chairman of the House International Relations Committee, said he asked the Iranian leader to act in accordance with his religious principles and because Esfandiari had been a tireless campaigner for U.S.-Iranian understanding.

Hamilton said a reply from the Ayatollah was relayed to him by the Iranian mission to the United Nations.

"He said that he was pleased with the letter that he had received from me and the commitment to peace and justice that I had expressed. He indicated that he had given instructions to address the issue of Haleh, he didn't use Haleh's name specifically, and that necessary measures would be taken as soon as possible," said Hamilton.

Esfandiari was released after her family paid bail of more than $300,000. It was unclear whether charges against her have been dropped but her Iranian lawyer, Nobel Peace Laureate and human rights campaigner Shirin Ebadi, was quoted as saying that she is free to return home.

In a talk with reporters, State Department acting spokesman Gonzalo Gallegos reiterated that Esfandiari and three other Iranian-Americans detained by Iran in recent months were not in that country on U.S. government business and should be released without conditions:

"Our position has always been that Esfandiari as well the other three had done nothing wrong, should not have been in the situation that they found themselves in and should be free right now," he said. "We are encouraged by this news. We will confirm whether it's true. And we continue to express our desire and belief that the others should be released as soon as possible and be allowed to join their families."

During her imprisonment, the 67-year-old Esfandiari was allowed to make only brief telephone calls to her mother and, according to Hamilton, was under severe stress and in need of medication for several ailments.

Shortly after her release Tuesday, she called her husband, Washington-based academic Shaul Bakhash, who told VOA she sounded generally well and delighted to be out of prison.

Bakhash, an Iranian-born professor of Persian studies, credited international appeals and officials of the Tehran government for the release:

"I am myself very grateful for the efforts of people in Iran and outside Iran, including Iranian officials, who helped get my wife released. And secondly I'm looking forward to seeing her back here, home, in the United States very soon. She has not been very well in prison, and she really needs some medical attention and a full checkup by her doctor," said Bakhash.

Iranian prosecutors said earlier this month that they had completed investigations of Esfandiari and Kian Tajbakhsh, another jailed Iranian-American scholar accused of subversion.

A third dual national, Ali Shakeri of a university-affiliated conflict resolution group in California, is also under detention but officials have not disclosed charges against him.