Mir Hossein Mousavi's 62-year-old brother-in-law is among the hundreds arrested in Iran's post election crackdown, the wife of the opposition leader said Thursday. Meanwhile, Mousavi warned that the country was becoming "more militarized" amid the turmoil, implicitly accusing the security forces of exceeding their powers under Iran's constitution, and suggesting that the "near-coup d'etat atmosphere" was a danger to Iran's Islamic republic. Police, the elite Revolutionary Guards and the Basij militia arrested more than 2,500 people in their heavy crackdown against protests that erupted in support of Mousavi after the disputed June 12 election. More than 500 of them remain in prison, including many top politicians from pro-reform political parties, human rights lawyers, journalists and activists. Arrests have continued in recent weeks. The turmoil has been the biggest challenge to Iran's ruling clerics in decades, and the Revolutionary Guards force has taken a prominent role in defending the leadership. US Secretary of State Hillary Clinton on Thursday said the upheaval has made it unlikely Iran will respond any time soon to the Obama administration's attempts to engage in dialogue with Teheran, its top rival in the region. "We've certainly reached out and made it clear that's what we'd be willing to do, even now, despite our absolute condemnation of what they've done in the election and since," she told the British Broadcasting Corp. "But I don't think they have any capacity to make that kind of decision right now." Mousavi claims to have won the election and that President Mahmoud Ahmadinejad's victory was fraudulent. Hundreds of thousands of his supporters marched in protests in the weeks after the election, until the demonstrations were shattered by the crackdown. Police say at least 20 protesters were killed, though human rights groups say the number is likely far higher. Mousavi's wife, Zahra Rahnavard, said her brother, Shapour Kazemi, was arrested more than a month ago. She said the 62-year-old communications engineer was "apolitical" and was detained only to put pressure on her and Mousavi. "We have tried all legal and peaceful means to try to win the release of him and other detainees," Rahnavard told the ILNA news agency in an interview released Thursday. She also sharply denounced authorities' campaign to depict the protesters and opposition movement as tools of foreign enemies seeking to carry out a "soft revolution" against Iran's Islamic Republic. Some hard-line officials have claimed that detainees have confessed to fueling protests on the behest of foreign powers. The opposition denies the accusations and says any confessions were made under duress. But this week, the political chief of the elite Revolutionary Guards, Yadollah Javani, called for authorities to make public any confessions to prove the conspiracy to the Iranian people "and rebuild the trust" of those that doubt in Ahmadinejad's victory. Rahnavard on Thursday said the Iranian people would not believe any "forced confessions." Of her brother, she said, "accusations of provoking riots or connections to foreigners ... are unimaginable." She warned those that are making accusations against detainees that "a divine anger will catch them and the nation will reject them." Rahnavard, a former dean of Teheran's al-Zahra University, campaigned alongside her husband in the election, a rarity for a candidate's wife, which made her a star among women and student supporters. Her original name is Zohreh Kazemi but she changed it in the 1960s when she became an activist against the US-backed shah, and she was a prominent activist in the 1979 revolution that brought the Islamic Republic to power. Mousavi, meanwhile, sharply criticized what he called the increasing power of security forces in the postelection crackdown. Iran was "heading in the direction of becoming more militarized, more security-dominated, something no one will welcome," he said. "The security forces must move in the framework of the constitution to minimize the loses in this near-coup d'etat atmosphere," he said Wednesday, according to ILNA. He said he would release a political platform soon calling for "activating neglected parts of the constitution" that ensure the people's voice is heard and that security forces' powers are kept in check. He did not elaborate. On Thursday, members of the pro-government Basij militia arrested the father of a 27-year-old teacher of the santour - a traditional Iranian instrument like a dulcimer - who was killed during a June 20 protest, the pro-Mousavi Norooz news Web site reported. Basijis arrested the father of Masoud Hashemzadeh from his Teheran home and collected black signs of mourning at the house's entrance, it said. Pro-reform Web sites have reported that families of slain protesters have been intimidated not to mourn publicly.