The three were held after they strayed into Iran from northern Iraq at the end of July, further complicating relations between Tehran and Washington that were already deadlocked over Iran's nuclear program.
Foreign Ministry spokesman Ramin Mehmanparast said that based on investigations, "the judiciary will make a decision and we know that they will be tried soon," English-language state television quoted him as saying.
Foreign Minister Manouchehr Mottaki said last month the three Americans would be put on trial, but did not give a date.
Also in December, U.S. Secretary of State Hillary Clinton repeated the U.S. government position that the charges were totally unfounded and the hikers should be released.
In November, Iran's judiciary announced espionage charges against the three — Shane Bauer, 27, Sarah Shourd, 31, and Josh Fattal, 27. Their families said they were hiking and had strayed across the border accidentally.
Under Iran's Islamic law, sharia, espionage can be punishable by death.
The case comes at a time of high tension between Iran and the West over Tehran's nuclear plans and after Iranian officials accused foreign nations of fuelling unrest after a disputed presidential election in June.
The United States cut diplomatic ties with Tehran after Iran's 1979 Islamic revolution. The two countries are now embroiled in a row over Iran's nuclear program, which the West suspects is aimed at making bombs. Tehran denies this.
(Writing by Fredrik Dahl)
