Reports from Tehran indicate the city is lined with security forces in anticipation of people responding to the opposition rally to join a silent march today on the anniversary of the last opposition demonstration, which led to the house arrest of Iran’s opposition leaders.

Eyewitnesses have so far informed Radio Zamaneh that main streets such as Keshavarz Boulevard are full of police and security forces.

Other reports indicate that security forces are closing down businesses at Haft Tir Square, which has been one of the main starting points for street demonstrations in Tehran.

In addition to the usual difficulty in accessing opposition websites, since the early morning hours even websites linked to the Ahmadinejad administration, such as Rejanews, Javan-on-line and Sepah news, have been blocked.

Since last night, several videos have been posted to YouTube showing people shouting chants from Tehran rooftops, a form of protest that began at the time of the 1979 Revolution.

Some news sites reported heavy traffic on the streets of Tehran last night, and the semi-official Mehr News Agency has attributed the heavy traffic to problems with the subway system.

Iranian opposition groups have called on the people to join a silent march in the late afternoon to protest against the house arrest of Iranian opposition leaders MirHosein Mousavi, Zahra Rahnavard and Mehdi Karroubi, who have been cut off from the outside world for a year now.

The opposition leaders had called for last year’s opposition rally in solidarity with the Arab uprisings. Last year’s rally led to several deaths and widespread arrests.

The Tehran governor has announced that any attempt tp start another demonstration today will be confronted by the authorities.