Updated

Iran has released from jail peace activist Ali Shakeri, the last of four Iranian-Americans imprisoned in recent months after being accused of stirring up a revolution, a judiciary spokesman said Tuesday.

Shakeri, a businessman and member of a California-based democracy group, the Center for Citizen Peacebuilding, was arrested while trying to leave Iran after visiting family. He was jailed four months ago in Tehran's Evin prison.

He and three other Iranian-Americans were charged with endangering national security — an accusation they, their families and their employers denied.

"He was released based on 1 million rials (about $110,000) bail last night. Shakeri is able to travel abroad if a ... judge permits him," Mohammad Shadabi, a spokesman for the judiciary, told The Associated Press.

The charges against Shakeri have increased tensions between the U.S. and Iran, already high over U.S. accusations that Iran is seeking to develop nuclear weapons and is fueling violence in Iraq. Iran denies both claims.

But in recent weeks, the country has reversed itself on the cases against the four dual citizens. Tuesday's announcement came as Iranian President Mahmoud Ahmadinejad is in New York to attend the U.N. General Assembly.

Shakeri's release comes less than a week after Iran released Kian Tajbakhash, an urban planning consultant with the New York-based Soros Foundation's Open Society Institute, from Evin prison where he had been jailed for four months.

In August, Iranian-American academic Haleh Esfandiari, who is the director of the Washington-based Woodrow Wilson International Center for Scholars, was also released from the Evin prison. She has since returned to the U.S.

Iran also this month allowed another Iranian-American, journalist Parnaz Azima, to leave the country after being stuck since authorities confiscated her passport in January. Authorities never imprisoned Azima but prevented her from leaving.

In a separate case, the Iranian government said this week it would allow the wife of a missing American who once worked for the FBI to travel to Iran even though it has no information on his whereabouts.

Robert Levinson was last seen March 8 on Kish Island, a resort off the southern coast of Iran, where he had gone to seek information on cigarette smuggling for a client of his security firm. His wife believes he did not leave Iran.