TEHRAN - A Japanese and two Canadian journalists have been arrested along with an Iranian working for "satellite channels," because they were reporting without permission on rallies in Tehran earlier this week, the Fars news agency said on Friday.

The cases are under investigation, Fars said, without giving further details of the allegations against the journalists.

The Tehran prosecutor said on Friday that his office was investigating the arrest of AFP reporter Farhad Pouladi while he was covering an anti-American rally in the Iranian capital on Wednesday.

The annual commemoration of the November 4, 1979 storming of the US embassy by Islamist students was overshadowed by a counter-demonstration by critics of President Mahmoud Ahmadinejad's June re-election.