Story highlights Iranian President Hassan Rouhani talks with CNN's Christiane Amanpour

There are three Americans known to be held in Iran and one who is missing after visiting the country

(CNN) Iran would be inclined to release American prisoners, such as Washington Post reporter Jason Rezaian, if the U.S. releases Iranians it is holding.

"If the Americans take the appropriate steps and set them free, certainly the right environment will be open and the right circumstances will be created for us to do everything within our power and our purview to bring about the swiftest freedom for the Americans held in Iran as well," Iranian President Hassan Rouhani told CNN's Christiane Amanpour on Sunday.

Rouhani said that anytime something can be done to help someone in prison, "nothing would make me happier."

There are three Americans known to be held in Iran and one who is missing after visiting the country.

Rezaian, a dual Iranian-American citizen, has been held in Iran for more than a year after being arrested and charged with "espionage and other offenses." His trial has been held behind closed doors.

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