Iranian Prosecutor Abbas Jafari Dolatabadi said Sunday that the country is ready to release one of the detained U.S. hikers on bail of 500,000 U.S. dollars, semi- official ISNA news agency reported.

Sarah Shourd's detention sentence has turned into a 500,000- dollar bail, Dolatabadi told a press conference, adding the detention sentence of the other two hikers has been extended.

The cases of the three Americans have been sent to the court, and "an indictment has been issued for the three U.S. nationals," ISNA quoted Dolatabadi as saying.

Iran said Thursday that it would free U.S. female hiker Sarah Shourd on Saturday morning, but it abruptly halted her release, saying "judicial proceedings in the defendant's case have not been completed."

The three Americans, Sarah Shourd, Josh Fattal and Shane Bauer, were arrested in Iran on July 31 last year after they illegally entered the country from its western borders.

They were charged with espionage last November, which the U.S. government considered totally unfounded. The U.S. government insisted that the three Americans should be freed.

In May, mothers of the three Americans were allowed by the Iranian government to meet their children in Tehran.

The U.S. State Department urged Iran to release all three detained American hikers on Thursday after Tehran announced that it would release one of them on Saturday.

"The hikers' release is long overdue," said Mark Toner, spokesman for the U.S. state department.

Toner urged Iran to release all three hikers instead of only one, saying the United States has called for their release" on humanitarian grounds for many, many months."