Iran has broadcast more footage of two detained Iranian-Americans over state television, in a case that has sparked outrage in the United States.

The television showed images of Haleh Esfandiari and Kian Tajbakhsh late Wednesday in a program called In the Name of Democracy.  Iran has accused the two of spying, and the footage shows a supposed confession by the Iranian-Americans.

Earlier Wednesday, U.S.-based Human Rights Watch expressed concern that Iranian authorities used coercive means to compel the two to make incriminating statements.

Tuesday, the U.S. State Department said it is appalled and outraged at what it called the mistreatment of the two prisoners after footage of them was shown promoting Wednesday's show.

Tajbakhsh is a New York-based urban planning consultant, while Esfandiari is a Middle East expert at the Washington-based Woodrow Wilson International Center for Scholars. 

Another Iranian-American, peace activist Ali Shakeri, also is being held in a Tehran prison.  A fourth, journalist Parnaz Azima, has been prevented from leaving Tehran.

The United States has denied any of the four are involved in spying.

Iran, which does not recognize dual nationalities, has told the United States the cases of the four are none of its concern.

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