An activist calls people to rally from the top of a crane Iranian police have placed opposition leader Mir Hossein Mousavi under house arrest, his official website says.
It says the move is intended to block him from attending a rally in Tehran in support of the protests in Egypt.
It is the latest in a series of arrests of people linked to Mr Mousavi and fellow opposition leader Mehdi Karroubi, also under house arrest.
Several opposition groups have vowed to take part in the protest, although officials have banned the gathering.
Although Iran’s establishment officially supports the Egyptian popular protests, it says the rallies are a “political move” by the two opposition leaders.
The authorities have stepped up security in the capital, blocked access to internet sites, and started jamming satellite news channels.
Emergency responders later pulled him off the crane Analysts say Tehran is trying to stop opposition groups from using the Egypt rally as a means to re-ignite anti-government protests – last seen in 2009 – against the disputed re-election of President Mahmoud Ahmadinejad.
In an unusual move, a man climbed a tall crane in central Tehran on Monday morning and began inviting people to attend today’s rally, the BBC’s Mohsen Asgari reports from the Iranian capital.
He threatened to kill himself if officials tried to approach him, but was later arrested by the police, our correspondent says. The activist was earlier mistaken for a young woman.
Also on Monday morning, Iranian police vans blocked the lane leading to the house of Mr Mousavi and disconnected his mobile phones and land lines, his website Kaleme.com said.
Last week, almost a dozen people close to Mr Mousavi were detained.
Send your pictures and videos to [email protected] or text them to 61124 (UK) or +44 7725 100 100 (International). If you have a large file you can upload here.
This article is from the BBC News website. © British Broadcasting Corporation, The BBC is not responsible for the content of external internet sites.