An image grab taken from footage broadcast 18 July 2007 by the Islamic Republic of Iran News Network (IRINN) shows US-Iranian Haleh Esfandiari talking to a camera at an unidentified place and time in Iran

Iran has released an Iranian-American academic who has been jailed in Tehran since May on security charges.

Iranian judiciary sources said Tuesday Haleh Esfandiari was released after her family paid bail of about $330,000. It is unclear, however, whether charges against her have been dropped.

Her Iranian lawyer, Nobel peace prize-winning human rights activist Shirin Ebadi, was quoted as saying Esfandiari is free to return home. But a human rights group, Amnesty International, said questions remain whether Iran will let her leave the country.

The United States welcomed Esfandiari's release from prison. But the State Department said Iran is still holding three other Americans who have done nothing wrong.

Esfandiari's husband, Shaul Bakhash, told VOA he is delighted by her release.

Former U.S. Congressman Lee Hamilton, who heads a U.S.-based academic organization that Esfandiari works for, the Woodrow Wilson Center for Scholars, said he had sent a letter to Iran's Supreme Religious Leader Ayattolah Ali Khamenei requesting her release.

Hamilton said Khamenei said he was pleased with the letter and promised to look into the case.

Esfandiari is a Middle East expert for the Woodrow Wilson Center. She said she was trying to create a network for making changes in Iran's system to improve democracy and the rights of women.

Amnesty International urged Iran to release the three other American prisoners. They are Iranian-American urban planner Kian Tajbakhsh, Ali Shakeri, who works for a university conflict-resolution group, and journalist Parnaz Azima of U.S.-funded Radio Farda.

Some information for this report was provided by AFP, AP and Reuters.