The head of Iran's judiciary has called for a crackdown on television channels and websites deemed to have been criticial of the government.
"The daily growth of anti-regime satellite channels and ... websites needs serious measures to confront this phenomenon," state television quoted Ayatollah Mahmoud Hashemi-Shahroudi as saying on Sunday.
"Those who co-operate with such websites and television channels will face prosecution," he said in a circular addressed to branches of the judiciary.
Since the disputed re-election of Mahmoud Ahmadinejad, the president, on June 12,
Iranian authorities have repeatedly accused Western governments and foreign media of interferring in the country.
The Farsi-language service of the UK-based BBC television network has been repeatedly criticised by Iranian officials and the company has said that its broadcasts had been blocked at points since the vote.
The BBC's correspondent in Tehran was also expelled over his coverage of the election.
On Sunday, Iran released Iason Athanasiadis, a Greek journalist working for the Washington Post newspaper, after he had spent more than two weeks in detention after being accused of "illegal activities".
But Maziar Bahari, a Canadian-Iranian national working for Newsweek magazine who is accused of acting against national security, is still being held.
The election was followed by days of mass protests by supporters of the defeated reformist candidates, who had branded the election as rigged.
A pro-reform body of religious leaders has backed the complaints about the vote, saying on Sunday that the outcome of the vote was "invalid".
"Other candidates' complaints and strong evidence of vote-rigging were ignored," the Assembly of Qom Seminary Scholars and Researchers said in a statement on its website.
"Peaceful protests by Iranians were violently oppressed ... dozens of Iranians were killed and hundreds were illegally arrested."
The assembly has little political influence but its statement is a significant act of defiance in the power base of Iran's religious establishment.
Aaron Rhodes from the International Campaign for Human Rights in Iran said that news of a split in Iran's religious establishment had been coming out of the country for some weeks.
"Many of the leaders of religious establishment are probably disturbed to have their government basically hijacked in what basically amounts to a coup by militaristic elements," he told Al Jazeera for Austrian capital, Vienna.
Meanwhile, an Iranian newspaper reported that 100 members of parliament sent a letter to the judiciary calling for opposition leaders to face trial over the post-election unrest.
An editorial in Kayhan, a conservative newspaper closely linked to the government, said reformists disputing last month's presidential elections were "dangerous".