http://newsimg.bbc.co.uk/media/image...07500629-1.jpg The clampdown follows Monday's show of defiance by opposition supporters
Authorities in Iran have announced sweeping new restrictions on foreign media, effectively confining journalists to their offices. The move comes as the powerful Guardian Council says it is ready to recount some votes from Friday's disputed presidential poll.
President Mahmoud Ahmadinejad was declared the winner and thousands of his supporters are rallying in Tehran.
But his rival Mir Hossein Mousavi and other candidates are seeking a rerun.
The BBC's Jon Leyne in Tehran says they may not accept the recount offer.
Several people died in a huge pro-opposition rally on Monday and Mr Mousavi urged followers not to take part in another demonstration planned for Tuesday, amid fears of new violence.
"This headquarters calls on people to avoid the trap of planned clashes," a Mousavi spokesman told AFP news agency.
See map of central Tehran
But there were reports of small groups of opposition supporters gathering nonetheless.
The opposition march had been due to take place in Tehran's Vali Asr Square at the same time as a demonstration there by supporters of Mr Ahmadinejad.
Thousands of the president's followers have converged there, some waving the national flag.
Media clampdown
The new restrictions on foreign media require journalists to obtain explicit permission before leaving the office to cover any story.
Journalists have also been banned from attending or reporting on any "unauthorised" demonstration - and it is unclear which if any of the protests are formally authorised.