U.S. Secretary of State Hillary Clinton urged Iran to release all Americans detained in the country, including three hikers arrested last month.
Clinton Saturday called on Iranian authorities to grant consular access to the three hikers, who were detained July 31.
Iranian television has described the three as spies who illegally entered the country.
Clinton said the United States also remains concerned about Robert Levinson, a former FBI agent missing in Iran since 2007. She also called for the release of American scholar Kian Tajbakhsh.
In related news, an American graduate student jailed in Iran for a few weeks and barred from leaving the country for nine months returned this week to Los Angeles. Esha Momeni was arrested last year and charged with acting against national security.
She was researching the Iranian women's' rights movement for her master's thesis at an American university.
Momeni is one of several Iranian-Americans detained in the last year on security-related charges. She says she spent 25 of her 28 days in jail in solitary confinement, and that she was repeatedly interrogated.
Momeni was eventually released on bail, but Iranian authorities confiscated her passports and barred her from leaving the country until this week.
Some information for this report provided by AP and AFP.