TEHRAN - Iranian security forces arrested four journalists, including one Japanese and two Canadian nationals, during the protests in Tehran this week, the semi-official Fars news agency reported Friday.

Thousands of opposition supporters, at the time the annual state-organised anti-US rallies were underway Wednesday, poured into Tehran’s streets to protest against the government of President Mahamoud Ahmadinejad despite severe warnings from security officials.

The opposition leaders Mir-Hossein Moussavi and Mehdi Karroubi accused the authorities of fraud in the June 12 presidential election to secure Ahmadinejad’s victory and do not acknowledge his re-election.

“A Japanese, two Canadians and an Iranian national working for a satellite television station were arrested during Wednesday’s rallies,” said the report, adding that they were covering the event without permission. The agency did not give more details of the reasons for their arrest.

The foreign press department of the Iranian Culture and Islamic Guidance Ministry is in charge of issuing press accreditation for all journalists working for the foreign media. The authorities were not immediately available to comment on the report.

Only a few days after the June vote, foreign media were banned from directly covering the street protests. On Wednesday, they were only allowed to cover the state-organised rally in front of the former American embassy but not opposition protests held in nearby streets.

The Iranian administration has branded the opposition foreign agents with a mission to undermine the ruling clerical system. Authorities have also labelled foreign media as instruments carrying out psychological warfare against the Islamic state on behalf of its enemies.