U.S. Secretary of State John Kerry says the issue of four Americans still detained in Iran was brought up by the U.S. side during every meeting at the recent Iran nuclear talks in Vienna.
"There was not a meeting that took place... where we did not raise the issue of our American citizens being held," Kerry told MSNBC.
Kerry stressed that the issue was even discussed during his final meeting with his Iranian counterpart Mohammad Javad Zarif in Vienna, before the historic Iran nuclear agreement was announced.
"We remain very, very hopeful that Iran will make a decision to do the right thing and return those citizens to the United States," Kerry said.
The Obama administration has said that efforts to win the release of Washington Post reporter Jason Rezaian, former U.S. Marine Amir Hekmati, Christian pastor Saeed Abedini and former FBI agent Robert Levinson would not be tied to nuclear negotiations.
Rezaian was arrested last year and is on trial on charges of spying. Abedini has been detained since 2012 for leading Christian worship services. Hekmati, a retired U.S. Marine who was arrested in 2011 while visiting his grandmother, was tried and sentenced to death on espionage charges. His sentence has since been reduced to 10 years.
Levinson disappeared in Iran in 2007. His whereabouts remain unknown.