The Iranian authorities are ready to release one of the three US hikers detained last year, state media report.
Tehran chief prosecutor Abbas Jafari Dolatabadi said Sarah Shourd, 32, would be freed on $500,000 (£325,000) bail.
Mr Jafari Dolatabadi had blocked a plan backed by President Mahmoud Ahmadinejad to release her at the end of the month of Ramadan as a good-will gesture.
Ms Shourd and two men, Shane Bauer and Josh Fattal, were detained near Iran’s border with Iraq on 31 July 2009.
Their families say they crossed a poorly-demarcated border by mistake.
Officials in Tehran said they had “suspicious aims” and that they intended to put them on trial for espionage. But they are still being held without charge more than a year later at Evin prison in Tehran.
US officials have said the three – all graduates of the University of California, Berkeley – are completely innocent.