Passions run deep under the Iranian chador as young lovers outfox the hardline clerics

Nazar Street in the heart of the ancient Persian city of Isfahan is crackling with sexual energy as Iran's Saviour Day holiday gets into full swing.

Nazar Street in the heart of the ancient Persian city of Isfahan is crackling with sexual energy as Iran's Saviour Day holiday gets into full swing.

When darkness falls, the shopping street heaves with young people, men in jeans and T-shirts, women hidden behind chadors, with a heavy police presence ensuring things do not get out of hand. There is the occasional thwack of night-stick across the shoulders of Isfahan's young blades, to keep them moving and discourage contact with the opposite sex.

At first glance, the Islamic strictures forbidding unchaperoned contact between unmarried Iranian men and women are being rigidly respected. But on closer examination one can see the "third generation of the revolution" as the young are often called, are busy with a strange new dating ritual.

The sudden movement of a boy's hand when he passes a young woman strolling down the street betrays everything. In the twinkling of an eye, the business is done and, as the groups of young men and women come together and separate, the lucky ones emerge with tightly rolled strips of paper on which are written the mobile phone numbers of those they have just bumped into.

"Collecting girls' numbers, it's the best fun you can have in Isfahan," says Hamid, a few metres from the uniformed police and the ever-present members of the Basij militia, the poorly educated but deeply religious country boys who repress dissent and protest across Iran.

This unaccountable militia force was formed more than 20 years ago by Ayatollah Khomeini to stamp out Gharbzadigi, or "Westoxification" in Iranian society. These days, the Basijis are used by the conservative clerics ruling Iran to keep a lid on the nation's wayward youth and those yearning for reform of its stifling religious code.

But the mobile phone is a potent weapon in the hands of the disaffected, as the totalitarian rulers of Serbia and Indonesia discovered to their cost. From under the billowing chador worn by Iranian women, the tell-tale tone of a piano concerto or Nokia chime is often heard. It might be an illicit contact with a potential boyfriend, a whisper of political dissent or a shopping tip to a friend. In the hands of millions of disaffected Iranians, the mobile phone represents power, and there is little the clerics can do about it.

The ruling mullahs also abominate satellite dishes. With numbing tedium, Iran TV's six official channels show censored feature films, dubbed to alter inappropriate plotlines. In topsy-turvy Mullah-land, boyfriend and girlfriend become sister and brother and kisses are forbidden. A mother may not even be shown kissing her son on Islamically correct Iranian TV.

Yet from the rooftops of any city sprouts a forest of locally made satellite dishes. "They are forbidden, but everyone has them," says Ali, toking deep on his hubble-bubble pipe in a tea-shop tucked into Isfahan's ancient Three Arches Bridge. "You have to buy two fake cards, one Farsi and one foreign for $7 [£4.50] and you have access to more than 80 channels."

There are periodic, ineffective, crackdowns by the religious police. But apart from confiscating the dish, there is little more they can do. More severe punishment – public flogging or worse – awaits those who commit adultery or have sex outside marriage.

Dissent in Iran is not confined to the young and the restless. Nearly all are devotees of the democratically elected, but politically neutered President Mohammad Khatami. And as far as the ruling clerics are concerned, Isfahan is a hotbed of insurrection. Here, Ayatollah Jaluddin Taheri, a revered and reform-minded cleric, recently threw down the gauntlet to the country's rulers by quitting as the city's Friday prayer leader.

"When I remember the promises and pledges of the beginning of the revolution, I tremble like a willow thinking of my faith," he said, in a devastating open letter to the people of Iran. He blasted the ruling clerics as a cabal of corrupt, hypocritical and power-hungry zealots. Iran's Supreme Leader, Ayatollah Ali Khamenei, was propped up by "louts and fascists, who sharpen the teeth of the crocodile of power". And the leader's turbanned associates were "just a gang of shroud-wearers".

But if Ayatollah Taheri had hoped to detonate another revolution, he must be sadly disappointed. On Saviour Day, when the Shia say prayers for the expected return of the Saviour Mahdi, the 12th imam, he was under house arrest.

Back on Nazar Street, the social revolution is in full swing. Two female shoppers begin to protest mildly about the strictures. They are interrupted by a lively 13-year-old girl pointing to the stifling chador she must wear when she steps outside home. "I want freedom, freedom not to wear this," the girl says. Her voice drips with contempt.