Defeated presidential candidate Mirhossein Mousavi has urged supporters to stage peaceful protests or gather in mosques tomorrow to mourn those killed after disputed elections that set off Iran's worst unrest since the 1979 Islamic Revolution.
Tens of thousands of supporters of defeated presidential candidate Mirhossein Mousavi gathered in downtown Tehran today for a fifth day of protests against last week's election, witnesses said.
Mainly dressed in black and also wearing wristbands and headbands in Mr Mousavi's green campaign colours, they assembled in Haft-e Tir square and streets around it, the witnesses said. Most of the protesters were silent and making victory signs.
One street leading to the square was packed for several kilometres, witnesses said.
At least one young woman held a picture of one of those killed during post-election violence that has rocked Iran since official results of the election were announced on Saturday.
One witness said police were blocking traffic on one road leading to the square.
As in previous pro-Mousavi rallies, demonstrators held pictures of him as well as green balloons, witnesses said.
Mr Mousavi earlier urged supporters to stage peaceful protests or gather in mosques tomorrow to mourn those killed after disputed elections that set off Iran's worst unrest since the 1979 Islamic Revolution.
President Mahmoud Ahmadinejad's victory against the reformist Mr Mousavi sparked demonstrations and bloody street battles in Tehran which killed at least seven people on Monday, while other protests flared up in cities across Iran.
"A number of our countrymen were wounded or martyred," Mr Mousavi said in a statement posted on his website today.
"I ask the people to express their solidarity with the families ... by coming together in mosques or taking part in peaceful demonstrations," said Mr Mousavi, adding that he would also take part in the day of mourning.
The bloodshed, mass protests over four days, arrests and a media crackdown focused world attention on Iran.
Iran's Foreign Ministry summoned the Swiss ambassador, who represents US interests in Tehran, today to protest at "interventionist" US statements on the country's election, Fars News Agency reported.
The Foreign Ministry communicated Iran's "protest and displeasure" over statements by US government officials about the outcome of last week's presidential vote, Iran's semi-official news agency said.
In Washington, the White House said President Barack Obama will continue to back the right of Iranians to peacefully protest the outcome of the election without "meddling" in Iran's internal debate.
"The president will continue to address those concerns and ensure that we're not meddling," White House spokesman Robert Gibbs told reporters.
The State Department strongly rejected claims that the US was interfering in the disputed June 12th election, pointing out that diplomats from other countries had also been summoned.
"I suspect we are in good company. As the president has said, we are not interfering in the debate that Iranians are having about their election and its aftermath," said State Department spokesman PJ Crowley. "This is not about the United States."
A senior Canadian diplomat in Tehran had also been called in to the ministry, Fars News Agency said. Several European ambassadors were also summoned yesterday.
Discord within Iran's ruling system has never been so public. The Mousavi camp is backed by traditional establishment figures, such as former presidents Akbar Hashemi Rafsanjani and Mohammad Khatami, concerned about how Mr Ahmadinejad's abrasive foreign policy and populist economics are shaping Iran's future.
Further protests planned for today and tomorrow are a direct challenge to the authorities who have kept a tight grip on dissent since the US-backed shah was overthrown in 1979 after months of protest.
In a stark warning, Fars News Agency quoted Interior Minister Sadeq Mahsouli as saying "no permission has been issued for a gathering or rally in Haft-e Tir Square" today.
State television has said the "main agents" behind the turmoil have been arrested with guns and explosives.
Tens of thousands of pro-Mousavi supporters defied authorities to rally in Tehran yesterday after the seven were killed in Monday's violence but international media were forbidden from leaving their offices to cover the event.
Security forces arrested a pro-reform activist and an editor today while a provincial prosecutor warned that those causing unrest faced the death penalty. An official inquiry was launched into an attack on university students.
Mohammadreza Habibi, prosecutor-general in the province of Isfahan, said: "We warn the few ... controlled by foreigners who try to disrupt domestic security by inciting individuals to destroy and to commit arson that the Islamic penal code for such individuals waging war against God is execution."
A reformist source said Saeed Laylaz, editor of business daily Sarmayeh, and activist Mohammadreza Jalaiepour were both arrested this morning. Mr Jalaiepour was detained at Tehran's international airport, the source said.
Iran's Interior Ministry ordered an investigation into an attack on university students which they say was carried out by Islamic militia and police. It came a day after Iran's influential speaker of parliament, Ali Larijani, condemned the attack on the dormitory of Tehran University.
One student activist who declined to be named said four students were killed during the violence. Tehran University denied anyone had been killed.
Supreme Leader Ayatollah Ali Khamenei, Iran's highest authority who has favoured Mr Ahmadinejad, has called for calm, allowing some ballot boxes to be recounted. But Iran's top legislative body, the Guardian Council, has ruled out reformists' demands for an annulment of the vote.
"Possible problems should be resolved following legal channels," the Ayatollah said said. "If removing these problems need recounting of some ballot boxes this should be done with the presence of the candidates' representatives," he said.
US president Barack Obama, who had urged the Iranian leadership to "unclench its fist", has said the protests showed that "Iranian people are not convinced with the legitimacy of the election". Mr Obama told CNBC there appeared to be little difference in policy between Mr Ahmadinejad and Mr Mousavi. "Either way we are going to be dealing with an Iranian regime that has historically been hostile to the United States," he said.
Mr Ahmadinejad has indicated that there would be no change in nuclear policy during his second term, saying the issue "belongs in the past".
Mohamed ElBaradei, director general of the International Atomic Energy Agency, said today Iran wants the ability to build nuclear weapons to gain a reputation as a major power in the Middle East. "This is to them the road to get that recognition to power and prestige and ... an insurance policy against what they heard in the past about regime change, axis of evil."