More than 2,000 Iranians have been arrested and hundreds more have disappeared since the regime decided to crush dissent after the disputed presidential election, a leading human rights organisation said yesterday.

“A climate of terror and of fear reigns in Iran today,” the International Federation for Human Rights , an umbrella body for 155 human rights organisations, said as it released the startling figures.

Last night 3,000 protesters tried to gather outside a mosque in Tehran where they believed that Mir Hossein Mousavi, the defeated presidential candidate, was going to speak. The police rapidly dispersed them and Mr Mousavi never appeared.

Having largely suppressed such protests, the security forces are engaged in a purge of dissidents in an apparent effort to decapitate Mr Mousavi’s so-called green movement.

Prominent Iranian actors, actresses, writers and singers are believed to have been seized at the weekend for supporting the demonstrators. Several opposition bloggers have fallen silent, probably because they have been detained. Almost anyone who dares to challenge President Ahmadinejad’s re-election is now considered an enemy of the state.

At least one senior Mousavi aide and other unidentified Iranians have appeared on state television to “confess” that the demonstrations were part of a foreign conspiracy against the Islamic Republic.

Human Rights Watch says that the Basiji — volunteer Islamic militiamen — are raiding houses, beating civilians and destroying their cars and other property in an effort to silence the nightly rooftop chanting that has become the opposition’s last means of peaceful protest. “The Basiji entered our neighbourhood and started firing live rounds into the air, in the direction of the buildings from which they believe the shouting of ‘Allahu akbar’ [God is greatest] is coming from,” a middle-aged Tehran resident said.

“Shortly thereafter my cousin arrived at our apartment. He was very shaken. The Basiji had entered their house and they had destroyed the doors and they had destroyed cars in the street. In every neighbourhood of Tehran people are talking about how the Basiji and other security services are coming into their houses and terrorising people.”

A senior Western diplomat said that the regime had achieved a short-term victory and was determined to press home its advantage. “It is a system which has been challenged and which now strikes back.”

The Obama Administration and the European Union said that they would have to engage with the regime to try to halt its nuclear programme, despite the charges of election-rigging and brutality.

David Axelrod, President Obama’s senior adviser, said: “Nuclear weapons in Iran and the nuclearisation of that whole region is a threat to that country, all countries in the region, and the world, and we have to address that. We cannot let that lie.”

Javier Solana, the EU’s foreign policy chief, said: “We would like very much that soon we will have the possibility to restart multilateral talks with Iran on the important nuclear issues.”

Ayatollah Ali Khamenei, the Supreme Leader, appeared on state television to mock what he described as the absurd and interfering criticism of Iran by Western leaders, and to call for national unity in the face of foreign threats. “If the nation and political elite are united in heart and mind, the incitement of international traitors and oppressive politicians will be ineffective,” he declared.

President Ahmadinejad hit back at President Obama’s increasingly blunt criticism of the regime by asking what had happened to his talk of change, and added: “If you continue your meddlesome stance, the response of the Iranian nation will be crushing. The response will cause remorse.”

Despite the regime’s intense pressure on Mr Mousavi to accept the election result, he issued another defiant website message yesterday in which he rejected the regime’s offers of a partial recount and renewed his demand for a new ballot. One Iranian analyst called it a “hell no, I won’t go” statement.

Mr Mousavi said that Mr Ahmadinejad and his cronies did not steal the election merely by stuffing ballot boxes, but that they broke electoral laws before, during and after the voting. “Limiting the probe into complaints about electoral irregularities to recounting 10 per cent of the ballot boxes cannot attract people’s trust and convince public opinion about the results,” he said.

Mehdi Karoubi, another defeated candidate, also rejected the regime’s offer. “How is it possible to answer controversies through counting some ballots?” he wrote in a letter to the Guardian Council, which oversees elections.

The opposition’s options look increasingly limited. With street demonstrations no longer possible, the battle is turning into a behind-the-scenes political struggle that could last many weeks or months.

Mr Ahmadinejad has the support of Mr Khamenei, the security forces, the judiciary and most government institutions. Mr Mousavi has the backing of two former Presidents, Ali Akbar Hashemi Rafsanjani and Mohammad Khatami. The Parliament and the clerics, two powerful constituencies, appear split.

Meanwhile the millions of Mousavi supporters who took to the streets after the election now lack a plan, direction and clear leadership. “Everybody is depressed, everybody is afraid,” said a young man from north Tehran. Another man, from Isfahan, lamented: “We have no one to lead us.”

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