Iran's supreme leader warned on Monday against any attempt to destabilise the Islamic republic as reformists called for a referendum to try to resolve the most damaging crisis since the revolution.
In a speech carried on state television, the nation's most powerful man Ayatollah Ali Khamenei again accused foreign countries of interference in the violent aftermath of last month's hotly-disputed presidential election.
"The enemies of the Iranian people, via their media, are giving instructions to the troublemakers to cause disorder, destruction and violence, while at the same insisting they are not interfering in Iranian internal affairs," he said.
"Anyone, no matter their rank or title, will be detested by the people if they lead our society towards insecurity," he said. "Our leaders must be viligant. Any word or action which helps (the enemies) will be contrary to the interests of our people."
Iranian leaders have repeatedly lashed out at Western nations, accusing them of stoking the unrest unleashed after the re-election of President Mahmoud Ahmadinejad in what the opposition protested was a fraudulent poll on June 12.
"While the meddling of foreign nations and their media in particular is clear, their pretence that they are not interfering in Iran's internal affairs is a sign of their dishonour," Khamenei said.
In particular, Iran has taken aim at Britain, arresting nine local staff at the British embassy in Tehran and expelling the permanent BBC correspondent. The last remaining embassy employee was released on bail on Sunday.
Khamenei's address follows a hard-hitting speech by former president and powerful cleric Akbar Hashemi Rafsanjani who said on Friday the regime had lost the people's trust, in his first public comments since the election.
Ahmadinejad's reformist predecessor Mohammad Khatami voiced a similar sentiment on Monday, and he and his supporters called for a referendum to resolve a crisis that has rocked the roots of the 30-year-old Islamic republic.
Khatami, whose 1997-2005 presidency saw a thaw in relations with the West, expressed concern that "public confidence in the system has been damaged," the ILNA news agency reported.
Hundreds of thousands of people took to the streets in the immediate aftermath of the vote but at least 20 people were killed in the ensuing violence and hundreds of protestors and reformists arrested by the regime.
The Association of Combatant Clerics, a group founded by Khatami, called for an independent referendum to try to find a way out of the crisis, although under the constituion only the supreme leader can organise such a public vote.
"During the recent election, the people's confidence was seriously damaged and for millions of people there is a belief that... the people's vote was altered and something other than the people's choice was announced," it said.
The clerics also denounced the campaign of "violence, murder and arrests" against protesters and warned: "Everyone will lose if this situation continues."
Rafsanjani, who lost to Ahmadinejad in the 2005 election and was attacked by the incumbent during this year's fiery election campaign, said on Friday he had drawn up a possible solution to the crisis.
"These are bitter times. I don't think anybody from any faction wanted it to end like this. We have all lost. We need unity more than ever," he added.
Ahmadinejad's efforts to form a new government have faced problems after even his own supporters came out against his choice of first vice president, the controversial Esfandiar Rahim Mashaie.
Mashaie's website on Monday denied media reports that he had quit only three days after being named, describing the reports as "lies" aimed at tarnishing the government.
Mashaie, whose daughter is married to Ahmadinejad's son, last year earned the wrath of many conservatives for saying Iran is a "friend of the Israeli people."