Iranian authorities have deployed thousands of security officers on the streets of Tehran, after a week of mass protests over a disputed election, BBC reported.
Witnesses said there were no rallies in the capital on Sunday, a day after 10 people were reported killed in clashes between police and protesters.
State media said 457 people had been detained over Saturday's violence.
The authorities have also continued a crackdown on foreign media - expelling the BBC's Tehran correspondent.
The corporation confirmed Jon Leyne had been asked to leave the country, but said the BBC office in Tehran would remain open.
Campaign group Reporters Without Borders says 23 local journalists and bloggers have been arrested over the past week.
The protests were sparked by the presidential election on 12 June, which officials said incumbent Mahmoud Ahmadinejad had won by a landslide.
Supporters of his nearest rival, Mir Hossein Mousavi, believe the election was rigged and have demonstrated since the results were announced.
But Supreme Leader Ayatollah Ali Khamenei has backed Mr Ahmadinejad and made it clear in a speech on Friday that no further protests would be tolerated.
Some analysts interpreted the ayatollah's speech as giving a green light for security forces to use live ammunition.
Iranian state TV reported that 10 people had died and 100 were injured when protesters and police clashed on Saturday.
On Sunday, thousands of security officers were out on the streets but protesters stayed away.
The BBC's Jeremy Bowen, in Tehran, says many residents of northern Tehran could be heard shouting from the rooftops "death to the dictator" and "Allahu akbar" on Sunday evening.
The chants have become a popular form of protest, and our correspondents says men, women and children joined in and Sunday's chanting was much louder than on previous days.
Mousavi's plea
Security forces continued to round up protesters on Saturday - with state media saying 457 people had been arrested.
Among the detained were several family members of Akbar Hashemi Rafsanjani - a powerful opponent of Mr Ahmadinejad.
Analysts said the arrests came as a surprise because Mr Rafsanjani is head of the Assembly of Experts - a cleric run group which has the power to remove the supreme leader.
All of Mr Rafsanjani's relatives were reported to have been freed by Sunday evening.
Meanwhile, Mr Mousavi, whose supporters make up most of the protesting crowds, urged them to continue their rallies.
"Protesting against lies and fraud is your right. In your protests continue to show restraint," a statement on his website said.
Analysts say Mr Mousavi's statements and the street protests his supporters have organised represent the biggest challenge to the state in the Islamic republic's 30-year history.
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