Iranian authorities have increased pressure on the leaders of the opposition movement, presidential aspirants Mir Hossein Musavi and Mehdi Karrubi, by arresting two close advisers.
Both detainees are members of a committee created by administration critics to investigate the cases of those believed to have been killed, detained, or abused in the postelection crackdown.
In the past two days, the aides were arrested in Tehran and the offices closed of groups that they set up to investigate alleged human rights violations since the July election.
Some fear the arrests and the raids could be a prelude to the arrest of the two opposition leaders themselves, who have both said the reelection of Iran's President Mahmud Ahmadinejad was the result of fraud.
Alireza Beheshti, a senior aide to former Prime Minister Musavi, and Morteza Alviri, an aide to former parliamentary speaker Karrubi, were reportedly arrested at their homes on September 8.
The offices of Karrubi and of his party, Ettemad Melli, were raided a day later, with documents and computers confiscated and editor in chief of Karrubi's website also arrested.
Musavi has issued a statement suggesting the arrests have led to “confusion and surprise” among those closest to the Islamic establishment and has called on supporters to stay calm. He also warned that difficult days are ahead.
"Be careful not to [allow yourself to] be provoked by them so that they don't harm your country as they are destroying themselves," Musavi said in a reference to authorities who are cracking down on those who dispute the official election results.
Opposition leader Mir Hossein Musavi insists his presidential bid was the victim of official fraud.
He charged that while Beheshti and Alviri are in prison, those responsible for the postelection atrocities are free and authorities claim they will investigate the crimes that were committed.
Musavi added that the arrest of someone like Beheshti, who is the son of one of the founding fathers of the Islamic Republic, Ayatollah Mohammad Beheshti, is a sign of more dreadful events to come.Preempting Protests?
The office of the Association for the Defense of Political prisoners, founded by prominent human rights activist Emad Baghi, was also stormed by authorities and shut down.
Analysts say the latest arrests could be also represent an attempt by authorities to intimidate Musavi's and Karrubi's followers and prevent them from protesting next week during state-organized Quds Day celebrations on September 18.
Karrubi has called on the opposition to demonstrate on Quds Day, where officially sanctioned anti-Israel demonstrations take place.
Musavi, in a statement issued on September 5, also called for more protests.
Mehdi Karrubi's son, Hossein, told RFE/RL's Radio Farda that the renewed crackdown is an attempt to intimidate his father, who has been defying authorities and publicizing testimonies of the alleged rape of detainees.
But Hossein Karrubi, whose father is a cleric and along with Musavi challenged Ahmadinejad in the June 12 presidential election, added that Karrubi is determined to persevere and that he will not be pressured into backing down.
"Anything might possibly happen," Hossein Karrubi said, "but what is clear is that [Mehdi] Karrubi is standing firm and he's serious in his work -- whatever might happen doesn't matter to him."Hardening Their Line
The latest events come amid calls by Iranian officials, including President Ahmadinejad, for the arrest of what they describe as leaders of the postelection "riots."
An Iranian lawmaker, Seyed Ali Mohammad Musavi Mobarakeh, has been quoted by the hard-line daily "Kayhan" as saying that action against Musavi is demanded by political groups and public opinion.
Morteza Alviri was mayor of Tehran from 1999-2002.
All eyes are now on this week's Friday Prayers, which will be led by Supreme Leader Ayatollah Ali Khamenei. The last time Khamenei led Friday Prayers was in the face of street protests in June, when he called for an end to street protests challenging Ahmadinejad's legitimacy.
A day later, on June 20, many Iranian citizens took to the streets to challenge Khamenei himself, who under Iran's Islamic constitution holds ultimate political and religious authority. Those demonstrators were met with force and a number of protesters lost their lives in a day that some are calling "bloody Saturday."
Hadi Ghaemi of the International Campaign for Human Rights in Iran said he believes the recent arrests and shutdowns are aimed at suppressing the truth about the postelection crackdown.
"Instead of investigating the information provided by [groups investigating deaths, detentions, and abuses], we see that those investigating are being arrested," Ghaemi said. "That means their activities are worrying for the authorities and they'd like to hide them."
One of the arrested aides, Alviri, said in an August 30 interview with "Etemad" that the hands of those investigating postelection human rights violations are tied.
In an interview with the online "Rooz" daily that was reportedly conducted a few hours before his arrest, Alviri said the current "silence" in Iranian society does not indicate "a lack of protest."
He added that there was a bomb in people's chests that could explode at any time. Radio Farda broadcaster Roya Karimi contributed to this report