Iranian President Mahmoud Ahmadinejad's media adviser was arrested on Monday in his office by the judiciary, the semi-official Mehr news agency reported, without giving a reason for his arrest.
A few minutes ago Ali Akbar Javanfekr was arrested after holding a news conference with local media, Mehr said.
Iranian media reported on Sunday that Javanfekr was sentenced to a year in jail and banned from journalism over a publication which was deemed to have offended public decency.
Javanfekr is also the head of Iran's state news agency IRNA.
Witnesses said security forces fired tear gas inside the building of the state-run Iran newspaper, where Javanfekr was giving the news conference.
Iranian authorities shut down reformist Etemad newspaper on Sunday after it published a scathing attack by Javanfekr on the president's rival conservatives. The daily is banned from publishing for two months for disseminating lies and insults to officials in the establishment.
Iran's conservatives accuse Ahmadinejad of being in the thrall of a deviant current of advisers seeking to undermine the authority of the clergy in the Islamic Republic's system of government.
(Writing by Parisa Hafezi; Editing by Rosalind Russell)