Chanting Allahu akbar” — God is greatest — and “Ahmadi, we love you” the army of hardliners poured into central Tehran in a massive show of strength for President Ahmadinejad.

After a weekend of violence by supporters of his relatively moderate challenger, Mir Hossein Mousavi, this was an exercise designed to reclaim the capital’s streets in the name of the establishment.

“The protesters are lying. There was no cheating,” declared Farang Kamalwand, 39, a woman in a chador who had travelled 450 miles by bus from Lorestan.

“We came to prove to people outside this country that we love and support our President,” said Karamollah Rahimi, a builder who had spent nine hours travelling from Lordegan.

The physical mustering of tens of thousands of fervent supporters from Mr Ahmadinejad’s core base among the poor, along with a massive uniformed and plainclothes security operation, was designed to intimidate. And it was not just their presence that the regime was using to quell dissent as it turned to electronic jamming and censorship to suppress attempts to publicise protests that were raging barely a mile from the presidential office, where Mr Ahmadinejad gave a surreal, Orwellian press conference.

He called his victory an “epic achievement” that made Iran’s brand of religious democracy, with its emphasis on ethics, a model for the world.

Mr Ahmadinejad dismissed the protests as unimportant, comparing the rioters to disappointed football supporters after a match. He said there was no evidence that he had stolen the election, and that his margin of victory — 28 per cent — was so great that it was absurd to question his legitimacy. “Don’t worry about it. Freedom prevails absolutely in our country,” he told incredulous foreign journalists.

The exuberance of last week, when Mr Mousavi appeared to be heading for a spectacular victory, turned to terror in the space of a few hours on Friday night as the regime unleashed its forces on the opposition.

All weekend, late into the night, squads of 30 or 40 riot police tore round the capital on motorbikes, roaring along pavements when the roads were blocked, and waded into crowds of chanting Mousavi supporters with their batons. Others charged up streets on foot, or rode around in black Toyota Land Cruisers. They used teargas, rubber bullets and stun grenades, and by Saturday night they had been joined by marauding bands of basiji — volunteer paramilitaries — waving the national flag and chanting Ahmadinejad slogans.

Nobody was spared. The Times witnessed an old woman in a long black chador being beaten in a doorway after she hurled insults at the police, a teacher clubbed to the ground by a basij as he tried to protect his demonstrating students and countless protesters carried away with blood streaming from their wounds.

One human rights activist called it a “Tehran Tiananmen”, referring to China’s brutal suppression of pro-democracy demonstrators in 1989.

Mousavi aides accused the regime of mounting a “coup détat”. His supporters retaliated by throwing stones, smashing windows, setting fire to buses and rubbish skips, and making barricades of burning tyres. “Mousavi is our President,” they chanted, and “What happened to our vote?” It was the worst unrest in the capital since the student riots of 1999.

There were reports of demonstrations in Tabriz, Siraz and other Iranian cities, but they were impossible to confirm because the regime all but shut down the telephone system. It blocked text messages, Facebook and several opposition websites to prevent Mousavi supporters from mobilising en masse.

The BBC and other news websites were jammed. Foreign journalists were denied extensions to their visas, ensuring that most would have to leave today or tomorrow.

Opposition newspapers were ordered to carry positive headlines dwelling on Friday’s massive turnout, but some refused. One that supports Mousavi ran a story about Mother’s Day on its front page by way of protest. Another, which supported Mehdi Karoubi, another of the four candidates, mocked the election with a headline proclaiming: “Karoubi comes fifth”. IRIB, the monopoly state broadcaster, has scarcely mentioned the riots.

Mousavi supporters are torn between fury, fear and despair. The green ribbons, headbands, shirts and bandanas with which so many were festooned last week have vanished — to wear them now would invite a beating.

Foreign journalists can no longer stand on pavements and openly interview Mousavi supporters. It is much safer to have snatched conversations with the occupants of adjacent cars in Tehran’s constant traffic jams.

“They’ve f***ed the country,” one Mousavi supporter declared. Another said: “I feel ashamed. I told so many people to vote.” And a woman, who complained that “it couldn’t be worse than it is”, added: “They do whatever they want. The people count for nothing.”

Times Recommends

• Both sides blame US for worsening relations
• Stieg Larsson: losing the plot over his cash
• Odd creature paralysed by incompatible parts