Two mothers of U.S. citizens detained in Iran for more than four months have urged Iranian Supreme Leader Ayatollah Ali Khamenei to release them.

The mothers of hikers Shane Bauer and Sarah Shourd made the appeal in an interview Friday with VOA (Persian News Network).

Bauer and Shourd, along with Joshua Fattal, apparently strayed across Iran's border in late July while hiking in northern Iraq.  The three were detained and have since been accused by Iran of espionage - a charge that could be punishable by death.

Shourd's mother, Nora, also made an appeal to Ayatollah Khamenei in an independent video released Friday.  She said the hikers made an "innocent mistake" entering Iranian territory and meant no harm to the Islamic Republic of Iran.

But in an interview with the French News Agency Friday, Iranian President Mahmoud Ahmadinejad said the three Americans illegally entered Iran in a "sensitive military zone."

President Ahmadeinejad told AFP "those who break the law will have to answer for it" and said "justice is independent in Iran and will decide."

The three U.S. hikers were visited by the Swiss ambassador to Iran in September but have not had contact with their families.

Switzerland represents U.S. interests in Tehran since the United States has no formal diplomatic relations with Iran.

Separately, a U.S. State Department spokesman (Robert Wood) on Friday welcomed the United Nations General Assembly's adoption of a resolution calling on Iran to respect its human rights obligations.