State television quoted a spokesman for the Foreign Ministry, Hasan Qashqavi, as saying that Iason Athanasiadis-Fowden (a.k.a. Jason Fowden) had been released in, what he described as the framework of Tehran-Athens ties.
There were no details on Athanasiadis' location.
Athanasiadis, a freelance reporter who had been working for The Washington Times, was arrested on or around June 19. Athanasiadis, a dual national with both Greek and British citizenship, is believed to be the only foreigner taken into custody by Iranian authorities in the post-election crackdown that has swept the country.
In the wake of the disputed June 12 presidential elections, Iran detained hundreds of journalists, bloggers, and activists.
The British Foreign Office said they are trying to confirm the report.
Qashqavi said Sunday that Athanasiadis had arrived in the past in Iran as a journalist using a British passport, and said he had been banned from entering the country for "violating the law."
Qashqavi said when Athanasiadis returned he got involved in "illegal activities" during the post-election unrest and that he was detained because of "behavior violating the profession of reporting." He did not elaborate.
Athanasiadis' parents have appealed for his release, calling him a reporter, photographer and filmmaker with "a particular love of Iran, and a deep respect for its cultural and religious traditions."
By Associated Press Writer Nasser Karimi; AP reporter Jill Lawless in London contributed to this report