CNN

WASHINGTON (CNN) - President Bush on Friday condemned the detention of four Iranian-Americans in Tehran, and called for their release - "immediately and unconditionally."

"Several of our fellow American citizens - including Haleh Esfandiari, Parnaz Azima, Kian Tajbakhsh and Ali Shakeri - are being held against their will by the Iranian regime," Bush said in a statement released by the White House. "I strongly condemn their detention at the hands of Iranian authorities. They should be freed immediately and unconditionally."

Earlier this week, Iran formally charged Esfandiari with trying to topple the government, according to an Iranian judiciary official, who also said that Tajbakhsh, a sociologist, is being detained in Tehran.

Esfandiari, 67, who works for the Woodrow Wilson Center for Scholars in Washington, was jailed in Tehran on May 8 and Tajbakhsh, an independent consultant and urban planner employed by U.S. philanthropists George Soros' Open Society Institute, was picked up two days later.